I meant a subconscious obligation, not a legal one. When somebody gives you a gift, it puts pressure on you (subconscious and social) to reciprocate. You see it all the time with youtube streamers, who frequently cater their content to their subscribers wishes to keep them happy. And to clarify, the streamers don't do this because their users are unhappy or protesting. They do it because they feel a sense of obligation to give their subscribers what they want because the subscribers were generous enough to give the streamer money.

For whatever reason, this phenomenon is completely lacking in the open source community. Instead, the opposite seems to occur. OSS developers are actively hostile toward their users, both vocally and how they react to criticism that their software isn't user friendly or respectful of their user's time. Anybody who has spent hours trying to set up a piece of OSS and then made the mistake of asking the developer for help can attest to this.