Absolutely agree with everything you've said. I had dreamed of a Libib[1] for my kitchen, but knew I would have to do all the painful data adding and it was too much of a bother.
The other big challenge I never resolved was how you'd account for e.g. using 1/4 cup of flour out of a bigger volume. Or taken to its extreme, cooking oil. How do you know how much your 'splash' is? You can't predict the remaining volume without a lot of fiddling to measure it and that defeats the purpose.
In the end, I opted for manual databases too, but they're pain to keep up-to-date. I still think there's a lot of value in a database for all-or-nothing style ingredients, but it was enough to deter me. I'm glad someone is less lazy.
The other big challenge I never resolved was how you'd account for e.g. using 1/4 cup of flour out of a bigger volume. Or taken to its extreme, cooking oil. How do you know how much your 'splash' is? You can't predict the remaining volume without a lot of fiddling to measure it and that defeats the purpose.
In the end, I opted for manual databases too, but they're pain to keep up-to-date. I still think there's a lot of value in a database for all-or-nothing style ingredients, but it was enough to deter me. I'm glad someone is less lazy.
[1]: https://www.libib.com/