>Are we obligated to pay for that?

Seeing as NASA and NOAA are paid for by taxes, it actually is. Now with the (decidely American) pedantics aside...

I agree with you in principle, but ultimately if people want to be paid they need to make that need or desire explicitly clear and on the record. Voluntary generosity can and will only go so far.

If someone releases their code under free-as-in-libre and/or -beer licensing, they don't get to subsequently complain if acts of voluntary generosity are "insufficient".