Poor people are the most likely to be exploited and the most likely to use their donated organs. It's been shown that empirically economically incentivising organ donation crowds out altruistic organ donation, a non negligible source of supply and that those who donate for money do not experience a long term economic benefit but do experience long term health consequences.
So what? That's up to them. People who buy organs are paying a fair price. Why do you want to infantalize poor people by denying them the opportunity to participate in the market?
By ignoring the reality of the situation you create a demand for people to cause severe risks to their health for short term problems, preying on the least educated group of people who have a severe information asymmetry... You also crowd out an altruistic source as it no longer becomes a societal issue but rather an economic one.
You also create an unnecessary class problem as middle and upper class people have access to organs, but not poor people who are the actual source of supply...
