[0] Your software is missing feature X = your park isn't clean enough
The monk handing over the book is the person who has done the work to write a pull request and gift it to the maintainer.
The request for a donation is the cultural expectation of reciprocity. A maintainer now feels pressure to accept the work of reviewing the PR. Yes, they can say no, but it feels bad and can motivate someone to stop maintaining open source software.
An open source project I initiate is not a "public good". I'm sharing it; I still own the copyright.
The monk handing over the book in the park has done no work on the park, they are a user NOT a contributor. In fact, probably a bunch of the trash I'm picking up are those pamphlets. I'm an atheist so the pamphlet is equivalent, at best, to a spam pull request.
> The request for a donation is the cultural expectation of reciprocity.
This is a completely different expectation that the open source expectation. I, personally, feel no guilt at all for telling people proselytizing to go away as I've done nothing to give them the expectation that their proselytizing would be welcome and most people proselytizing expect to be rejected constantly. Contributing back to open source is expected and usually desirable so the expectation that the contribution will be accepted.
Also, the monk is ASKING FOR A CONTRIBUTION not giving one.
If you feel a large degree of ownership over the codebase, you'll also be irritated at including someone else's code/design style. Like having someone else's voice in your head. You could go through the PR and request changes to conform to your code/design preferences, but that would take a lot of your time and also a lot of the contributor's time (and be very likely to frustrate the contributor). It would probably just be easier to rewrite it yourself in your own style. Or just let all that stuff slide. But then your project is less "your" project, and you might not get the same sense of gratification working in the codebase.