There's a big difference in paying for something because you need it done and paying for something you don't even necessarily want but someone did anyway. If you're thinking about "what did this software cost?" and engineering time, then it sounds like the software is already a business need and is being considered from a business perspective.
If I'm furnishing my new empty home and don't have a couch, I'm going to shell out approx. $2,000 for a couch because I need one.
If my house is completely furnished and someone shows up at the door with a couch, I'd either turn them away completely or possibly offer them a small amount after evaluating whether I can even accept it.
IMO claiming that rewarding people for doing any random OSS work they'd do anyway devalues software development in general is concern-trolling.
Before: This costs nothing but I’m avoiding paying for the engineering time that is $$$.
After: $20 an hour is the going rate for developing this sort of software.