I think a better comparison re: cars would be if inspections could only be performed by Ford or GM and the inspection rules were made by them instead of the government. They could say: we’re no longer passing inspections on models older than 5 years old, or if you used non-approved oil or filters the toll roads are gonna block you. They could put ads on your infotainment system and say you won’t get an inspection pass if you block them or replace the infotainment system with something else. Did you bypass the subscription lock on your heated seat? No more highway driving for you.
From the related post linked by op, it’s described as just a portion of the managed instance hosting fee going back to the project devs. So if you pay them to host a lemmy instance, a small cut goes to Lemmy devs. Doesn’t seem sketchy at all. Seems to have nothing to do with monetizing the instance itself, which could be funded by voluntary donations as normal or you could probably do membership fees as some instances do. It seems this is just about giving funding to the software devs. Hopefully this encourages other managed hosting providers to also give a cut of their revenue to the software they are using for their business.