@dasrecht@chaos.social If you're sufficiently invested in this problem to try and solve it, I think a good place to start would be to simply reach out to some prolific contributors on Google Maps, and ask them (non-judgmentally, and without asking them to do anything) what is motivating them to do this 🙂
And try to understand their motivations and what draws them to it in as much detail as possible, crucially *without* trying to convince them to "come over to OSM". That should provide a wealth of information as to what's missing, though be prepared for the first answer not being the 'real' answer but rather a simplification. The nuance is important.