Software development typically requires at least a computer (a Mac for MacOS and iOS development), internet service, and electricity.

Dwarfing those, though, is the significant time software development takes. For OSS, the time is donated, whether by individuals or by corporate sponsors who sometimes dedicate employee hours to projects of particular value to them. But in either case the donator has to be in a position to afford it, which typically means significant income from other means.

> But in either case the donator has to be in a position to afford it, which typically means significant income from other means.

Even if someone has the time and resources to contribute to OSS, it does not automatically follow that they should be willing to spend said time and resources on notarization (of all things).

Put another way, not every purchase is worthwhile just because you have a million dollars in the bank.

The resources, time and hardware implicated in the production of open source software, when all added up represent far more than US$99, in terms of value.

You may say that a FLOSS project has no bank account, but it does not have $0 budget (unless it has no value, and is produced with nothing of value, by noone whose time has value).

You don't pay the developer fee with "value", you pay it with legal currency. Which requires a bank account or credit card.