I am also from Germany and get payed for donating thrombocytes at my university hospital. The compensation is actually quite substantial imo at (up to) 75€ per session, which can be done every two weeks. The money is however mean to offset the time required, not the thrombocytes donated. So it is correlated to how long it takes.

You get 15€ (?) for up to 15min (if they have to abort very early for some reason or at your first visit where they just draw blood to test), 50€ for up to 1h (which equals to 1 instead of 2 pack of thrombocytes, usually done at your first real donation or if you maybe dont have enough for 2 on this particular day), and 75€ for anything over 1h (which is the norm).

Timewise the hospital is on the outskirts of the city, so most will have to travel a bit, then you have to fill out forms, have a quick talk with the doctor, and finally depending on your parameters it takes anywhere from ~55-70min to extract, during which you are tethered to a machine (which takes out some blood, then seperates out the thrombocytes with a centrifuge, pumps back the rest, and repeat).

One could get philosophical about the topic, but from a practical perspective the money makes a lot of sense imo:

• It costs them a lot of money to investigate new prospects, so you want reliable repeat donors

• Each donation already has other costs associated with it. Like for example the kit used during extraction, the staff handling everything and so on. So even those 75€ are just one more expense among many, and from donation to usage probably vanish in the overall costs.

• For the donor it is quite a substantial time commitment, especially when done regularly every two weeks. Unlike for example full blood donations you'd maybe do twice a year. And you should be reliable and not randomly cancel at the last second, so ideally it also has priority over some other things in your life.

• the small amount of blood that remains inside the machine is sometimes used for other research (if you agree to it, which i do)

From my own experience i can say that i might still do it without, but certainly not at the same frequency. And considering the time and effort required i don't think anyone could be blamed for doing it less frequently without the incentive. So at least in this case it imo is a fair trade and net positive. Although it does also help that this is a university hospital that directly uses it themselves, rather than a for profit company.