Companies should be required to pay if they take the software, modify or fork it, and then sell it to others. That’s the only case in which I think anyone should be paying for libre software.
For example, the linux kernel is used by android. Google modifies the kernel source and sells it to phone manufacturers. Linus Torvalds (and the rest of all kernel devs) deserve a stipend for the use of their work to generate profit. Also, the modifications should be legally required to be open sourced if they don’t pay.
My point was that the selling of others’ code is NOT part of the agreement. For that, the volunteers deserve payment. Technically, it’s a violation of the GPL to modify the code, and distribute binaries of it without the source. Companies get away with that all the time.