If I understand this right, is the idea something like this?
Developers using FOSS libraries (even if their code is not necessarily FOSS itself), along with the end users of those products, don’t have to pay for it in any way. Because of that, it’s an “external cost” that no one thinks about even though most projects do need some kind of funding?
That’s half of it. But it’s worse than that. You’re considering the case where a non-zero price would fund existing projects that need work. Now consider how much value FOSS could create if we paid enough for it so that more people went to produce more of it. Microsoft wouldn’t exist today or it would use FOSS and either way everyone would pay way less for MS or MS-equivalent enterprise products. There would be a ton of freed up resources that could go towards other useful endeavors. But who am I kidding, they’d go into stock buybacks. 🫠
See my other comment for more detail.
