[tait]

That's right, and I have taught that point to trainees. However, there is a subtlety and I am sharing it as penance for having taught incorrectly:

The FDA does allows blood donation by paid blood donors. The blood must be labeled as from paid donors, but it is legal.

See https://www.statnews.com/2016/01/22/paid-plasma-not-blood/ for example...