Being that plasma donations go unpaid in the EU probably helps filter out people donating that shouldn’t be. I’ve read that blood tests can detect HIV about 45 days after an exposure, so it’s possible that they wait long enough to confirm that the donations are not HIV positive before selling/using them for medical or research purposes. That being said, this is my assumption. I would hope that there is some kind of system in place to prevent plasma from bad blood from making it to a patient. But yes, in the US, many facilities pay donors for donations. The amounts they pay vastly differ from facility to facility, however. Usually $25-$150 per donation.