> selling kidneys doesn't preclude us having the same thorough screening process we have now, although it means there may be people who try harder to game the screening process.
Nothing I have said really even touches on the topic that that safety could be impacted by people trying to game the screening process, though it is of course a legitimate concern.
> i just don't see kidney donation as being a significant enough harm to outweigh the harm of the recipient not getting the kidney.
I don't disagree that kidney donation is a net good. The question is what you do with that opinion. You could defend the idea of a "kidney draft", where some random selection of the population gets forced by the state to "donate" one of their kidneys; though I suspect a lot of the proponents of a free organ market would be uncomfortable with that idea, as would I. The difference is that I view financial coercion as just as much of a problem as state coercion.
> if we're worried about people being financially desperate, we should allow organs to be sold and build a stronger social safety net
I agree! If there was a social safety net which reliably kept people out of desperate poverty, I would be less worried about financial incentives.
The safety net needs to come first, however.