I can’t resist mentioning that it is illegal to sell organs, or even parts of organs. Note that it is possible to cut out a part of a liver and use that for transplant - someone doesn’t need to die for their liver to be useful. However, the free market for livers is banned, and, surprise surprise, there is a shortage. Because it’s not worth most people’s effort to donate.
Egg donors, blood donors even sperm donors get paid.