Kidneys and retinas are actually an easier case, compared to prostitution. Transplants are difficult surgeries that require hospitals and specialized labor, so

Kidneys and retinas are actually an easier case, compared to prostitution. Transplants are difficult surgeries that require hospitals and specialized labor, so they are very easy to regulate. Of course people should be able to sell their organs if they have permission of a doctor (who would get in trouble if they authorize a coercive transplant, just like euthanasia) and the recipient (who should be decided ahead of time to discourage organ hoarders and ensure compatibility)