Earlier quoted context omitted.
Not all open source developers want money for their open source software. You think collecting money using someone else's hard work isn't a bad thing. A hard work that the person explicitly went to the trouble of making free and abstained from any income derived solely from it.
Lots of people want to make money from their open-source projects, directly or indirectly.
Mainly because that's precisely what open-source isn't: it's not distribution of software services. There isn't a consumer-producer relationship.
Indirectly is what works great: someone with a vested interest pays an open source developer for his expertise to make sure the open source project continues on. The developer is backed by the full extent of labor laws, welfare services and all other work-related niceties her or his country might have. Or the developer provides a service with clear boundaries which other people pay for, helping provide income for the project's developer and possibly giving it guidance.
Directly there's none of that. There's only people giving money to someone who now has to bear the full legality of it, unaware of the purpose or source of said money. If they don't want it, don't force it on them. Not to mention most projects which want money already have a system set up for it, a system which they explicitly decided was the best for them.
There are loads of other ways to support open source developers other than forcibly putting them in a situation in which they need to hire a lawyer.