Where is this happening? AFAIK most (all?) of the EU strictly forbids being paid for blood or blood component donations outside of very specific research.
(As a donor I tried to sell blood when I couldn't afford rent and food, but it seemed impossible.)
All over Germany. As a student, I donated blood plasma which was way more lucrative (until the US banned plasma imports and killed the market). You can donate plasma more often (up to 5 times in 14 days), and IIRC I got 17€ per session, 30€ for every 3rd session, and 50€ for every 5th session. Yes, they had a consitency-reward schema going on in order to get you engaged and keep coming back. Plus, also wanted to thwart off people in financial needs that desperately need money the next day (like drug addicts).
Must be referring to the little money they give you for travel expenses and breakfast (so you don’t pass out) is typical in many places. But is in no way a compensation, and mixing that topics is really confusing things.
(As a donor I tried to sell blood when I couldn't afford rent and food, but it seemed impossible.)