A few quotes:
I always charge extra for custom agreements including NDAs or proprietary licenses (I typically offer a significant discount if the code I write for them can be open source).
Remember: the customer pays for their costs, not you.
But the point is, aimlessly using volunteer-only projects in commercial applications is precisely what causes asymmetry in open source. And when something goes wrong (think Heartbleed and log4shell), people clamor to “fix open source funding” when really, money isn’t the solution at all. It’s boundaries.