I'll admit I was wrong about people having shorter lifespans. However, I wouldn't say that source is convincing me of the opposite:

Why do living kidney donors tend to live longer? There are several reasons. First, potential kidney donors undergo rigorous medical screening, and only people in the best of health are accepted as donors. So living donors are already healthier than the general population before they donate, and would probably have lived longer anyway.

Second, living kidney donors tend to take excellent care of themselves post-donation. Undergoing donation surgery and living with a single kidney gives donors a heightened awareness of their own health and the importance of healthy habits. The tendency of living kidney donors to take extra good care of themselves by exercising, eating right, and avoiding poor habits like smoking and excess alcohol consumption, can translate to a longer life.

Healthy people live longer lives, them donating a kidney isn't related to that. Also, an organisation devoted to convincing people to donate their kidneys is obviously going to be pro-kidney donation. But if we go back to the original article, the goal is to expand kidney donation. Kidneys are usually donated by very healthy people, so losing a kidney doesn't affect them all that much, but what about unhealthy people? Someone desperate enough to sell a kidney for money (or "tax credits" or whatever) isn't probably in the best health mentally or physically (financial woes tend to do that to people). Don't misunderstand me, I'm not anti-organ donation, but I do not trust the US healthcare system to do it in any positive way, like everything else over there, it will be abused for profit, and that will mean people will be at risk.

You mentioned that you're Canadian, look at the recent euthanasia procedures passed in your country. Something pushed as a means of "helping the terminally ill die with dignity" has been used to encourage the disabled or mentally ill to kill themselves to save the state's money. We shouldn't examine a proposal based solely on their slick, shiny pitch. They're always going to make it sound like a 100% positive thing that we'd be fools to not adopt. But they're trying to sell the idea to us, they're not trustworthy. We should examine their proposal based on how it could be misused or abused, whether it could lead to a worse situation, whether the proposal will even fix the problem it claims to be trying to fix, or if it will just be used as another avenue to funnel money to the wealthy.

Also your tone policing has no place here. If you're so fragile that someone being snarky on the internet is something you can't handle, you should leave.