For example just now I tried answering “see” for 視 (look at) but that was counted as wrong. Is it to make you distinguish the various kanji with similar meanings? I think there should at least be a warning/hint when you enter such a similar meaning.
On jisho “see” is listed as one of the meanings of this kanji.
I think WaniKani was designed to err on the side of less definitions, not more, perhaps to distinguish nuances. You can add user synonyms to partially address this limitation if the word was not blocklisted.
I wish they added the other definitions to the allow list or they could show a warning that tells you you’re close but they want a different word, like they have for some other items.
Unfortunately, that’s a limitation of a computer system. You can’t catch all definitions, or else you’ll end up with so many additions from suggestions that the meaning gets diluted. Something that’s also a danger with user synonyms, which is why some are blacklisted.
In the end though, it’s a machine. There’s always going to be some rigidness.
Only way you can be sure to be fine in terms of nuance and immediately catching a broader range of meaning, pushing you back to what’s more correct if you’re close enough, is a real human being. Preferably a private tutor that can attune to your pace. But even then there will always be blind spots.
Checking a couple of my 国語辞典, this particular kanji seems to have the nuance of 注意深く見る, which in English could be “to look at carefully”.
Honestly, I completely forgot about Wanikani’s “look at” meaning. I would have probably guessed “see” or “vision”.
I’ve found in general, WK wants you to learn one and only one word for each kanji you learn. I think the idea is, just like the one reading idea, not to overwhelm you with too much to learn at once and to keep things simple. But I think it’s really silly, WK often wants you to pull up very specific ideas for each kanji. But especially when going back to older material, what I’m going to remember about a kanji is the vocab that it’s in not the specific word I learned the first time I looked at it. And actual kanji meanings are the furthest things from specific.
So even in cases where the vocab item would have a whole collection of alternate meanings, the kanji will not. Which means in order to be productive with your time, you need to put in a whole bunch of extra synonyms. Like 視 is a good example, there are so many different synonyms for “see” that WK could be asking for (“view” “look at” “glance” “sight” “observe” etc.). I’m gonna remember is 6 months to a year that this has something to do with sight but I’m not gonna remember the exact “sight” terminology it’s expecting.
At this point what I do is whenever I do lessons I look at the full page for the kanji on WK and I look at all of the kanji’s vocab. Then I personally check to see if the vocab matches the given meaning and add tons of synonyms up front if it doesn’t. It would be nice if I could do this in the normal lessons page, if lessons would show you all of the vocab for a specific kanji and not just a handful of them.
I noticed that WK vocab items often accept definitions listed on jisho (JMdictDB) even if they are not listed on WaniKani. Therefore I’m not sure if it has to do with the rigidness, it could be be a conscious decision to limit accepted answers for kanji, after all there are way less kanji than vocab items and kanji usually have fewer definitions than words.
Checking a couple of my 国語辞典, this particular kanji seems to have the nuance of 注意深く見る, which in English could be “to look at carefully”.
Honestly, I completely forgot about Wanikani’s “look at” meaning. I would have probably guessed “see” or “vision”.
Interesting, I didn’t know you could find kanji definitions in dictionaries. Might take a look next time I’m confused or unsure about a kanji.
My understanding is that kanji meanings are slightly vague/general and depend on the word they are used in. Not to mention that a kanji can have multiple seemingly unrelated meanings. I doesn’t seem that either definition, “look at” or “see” is more accurate than the other for this kanji.
I’m using a script to undo answers. Originally I was using it to catch typos. But a lot of the times I’m getting kanji from early on before I got a bit heavier with synonyms because I got through a cycle of all the potential ways you could translate this in English before hitting the one Wanikani wants the 4th or 5th attempt or so. None of my answers were wrong. They were just not the exact one that the site demanded.
(Not counting the rare few times I double guess myself and look up what it actually is on Wanikani itself and get some weird reading that would’ve never popped into my head, or shown up in any dictionary. That’s happened before.)
Unfortunetly, I am currently in the cursed position of only liking to do reviews on the default mobile website. So no undo button for me, I must cheat in other more laborious ways.
I should have been more clear.
My two sources are 三省堂小学漢字学習辞典 (Sanseido Elementary School Kanji Learner’s Dictionary) and 明鏡国語辞典. 明鏡 for some reason has entries for kanji that don’t typically appear by themselves. Entries are very brief sentences attempting to ascribe a general meaning to a kanji. I definitely don’t consider either as giving a “definition” to a kanji.
Personally I agree, but I guess there is a nuance between “look” and “see” if the information on some random internet page can be trusted. As a native English speaker myself, I should probably know these things.
The difficulty is that of course there isn’t really any English (or other language) word that actually equals any Japanese word (with a few exceptions, though even loanwords often have very different meaning/nuance). So I think it’s good to have a sort of placeholder as a starting point (e.g. “see”, “look at”) that’s “easy” to remember and differentiate while learning, and then over time we can develop our own internal meaning/understanding of the Japanese term itself based on usage/experience, unique to Japanese, which will always be much richer and more memorable than the sort-of-stick-figure-drawing idea we necessarily begin with. And that is so cool. 
Similar to what @brenty says, our approach is to limit the number of meanings for kanji so as to efficiently encapsulate the key central idea(s) associated with it, and then reinforce those meanings and flesh out further nuances/uses in related vocabulary. As @whipmywillows says, that does have the drawback that once it’s been a while since a kanji has come up in a review it might be harder to recall what that core meaning is now that you’ve learned other nuances/uses, but we still think there is value in keeping the focus on the main meanings, and we do endeavor to add additional meanings to the allow list when appropriate.
In the case of 視, the kanji connotes a sense of intention behind the act of “seeing.” In other words, it’s a deliberate type of looking at something, so we reflect that by using the meaning “look at,” which suggests both intentionality and that there’s a target object behind the act.
The relevant meaning in Kadokawa’s Shinjigen (新字源) kanji dictionary is as follows, with my translations/comments:
❶みる。
→ “to look”/“to see” (below sub-meanings flesh out the nuance)
㋐気をつけて見る。「注視」
→ “To look at [something] carefully/with care.” (or to look at something with attention)「注視」＝ “close observation” or “scrutiny”
㋑はっきり見る。くわしく調べ見る。「視察」
→ “To look clearly at. To visually examine in detail.” 「視察」＝ “inspection” or “observation”
“Look at” best encapsulates what the above nuances have in common. The 監視 and 凝視 vocab we teach probably get at the “examine” and “look with attention” types of nuances above most clearly. Vocab like 視覚 and 遠視 show how the kanji, expanding on the above nuances, has ended up being used for scientific/medical words. There are other nuances in the dictionary, but they are rather niche/uncommon.
So “see” as a meaning for the kanji is ambiguous, because in English that could also be a more passive act, say when you just happen to see something, which is why we don’t accept it as an answer. I’ve added a sentence to 視’s meaning mnemonic to imply this is a deliberate kind of looking, and also added “see” to the warning list so that people will know we purposefully don’t accept it.
Thanks for bringing this up! Hope the explanation helps.
Thank you for the very detailed explanation of the reasoning behind the choice, and for adding the warning. I can follow the logic and consider my question answered.