Then the payment can go to a fork. If the maintainer really wants to keep his vision for the project and others are literally voting with their wallets for something else, why would that be a problem?

With Polar today only the maintainer receives the pledges once an issue/feature is completed. However, we're working on the ability for maintainers to split that with any potential contributors. It's definitely an important feature and part of our model. Just something we decided to scope out from the initial launch – in the interest of launching early and building in public.

An important distinction between Polar vs. traditional bounty services though and regarding your point is:

Everything goes through the maintainer(s) and we're equipping them with the insights, capital and tools to reward their contributors. While bounty services allow anyone to post a bounty and anyone to pursue it. However, ultimately it needs to be reviewed, merged and maintained indefinitely by the maintainer(s). By ensuring it all flows via maintainer(s) it:

1. Rewards maintainers as well – key given their efforts

2.Guarantees maintainers are aligned & behind pledges first. Combined with in control on how to expose, delegate and reward it. Avoiding unnecessary friction, bad faith and overhead if such alignment is first made during PR.