We should outlaw firefighting. We’re exploiting people who need money, coercing them to put themselves at risk so that others may live. What kind of society allows people to sell their own bodies like that?
On an unrelated note, it’s still illegal to purchase kidney transplants everywhere but Iran. 12 people in the United States alone die every day waiting for one. There are few if any long-term negative health impacts of kidney donation, though it does require taking some time off which anyone but the rich would need to be compensated for.
There are probably ways to mitigate the incentive risks in paid organ donation, or opt-out organ donation, but given how conditions are it won’t happen. Even something as simple as “yes Dr. Richmann you may purchase a higher place in the organ recipient list, but you must pay for the procedure for four other people”.