You know, I was reading that article while writing this up, but I thought I checked my examples to make sure it wasn’t just that. Really now I see that the only one that isn’t just that is 見る vs 見せる, which are both transitive.
[Edit] - Note for anyone who might see this looking for help. I think one of the reasons I thought this might be separate from ichidan vs godan is that it did not click that “to do something with no object” falls into the same class as “to have something done to you”.
On a side note, active voice and passive voice are different to transitive and intransitive verbs. Active/passive voice is indicated by conjugations of the same verb - for example, 食べる = active, 食べられる = passive; 飲む = active, 飲まれる = passive. The Japanese terms for these are 能動態 (active voice) and 受動態 (passive voice)
So, I have used a mnemonic that’s helped me a lot. It’s not always applicable, but basically, because of 上げる, I think, “I deserve a raise for being げ”. And if you’re not げ, you can think of me, toiling away fabulously, deserving a raise.