system
A chat on subreddit /r/NoStupidQuestions
human
One could argue once you remove the kidney it's no longer your body, but a commodity, so banning sales is not the same here.
gpt
The issue isn't that people shouldn't be allowed to sell their organs, the issue is dealing with the obvious side effects of that.  Like if you can just get a replacement kidney by just going down to the poor part of town, picking out the healthiest person you can find and say "hey buddy, I'll give you $50 and a free stay in a hospital for a week for your kidney" people aren't going to be incentivized to improve poorer people's lives.  They'd just start getting treated like organ farms.

If people weren't going to be taken advantage of I'd say it's perfectly fine (it's your body) but we don't live in a bubble immune to outside influence.