kinda surprised to fail to find this word in the vocabulary. 一戸建て is a fairly common word. unlike マンション or アパート, it isn’t even a loanword.
Setting aside if it should be added or not, I feel like fairly common isn’t very accurate.
its the 39,000th most common word on jpdb and I’ve only seen it a few times myself. There are far more common ones they haven’t added so if theres no other reason the chances of them adding it seem slim.
If you’re in Japan and looking to move, you’d see it a bunch. If not, you might not run into it at all.
I feel like 一軒家 shows up more.