Think of it in reverse. The survivor of the accident that doesn't happen donates their organs to themself. Organ donation is just one means to increase survivorship, but there are other means as well.

You answered your own question. By the time we see a serious drop in auto fatalities because of mass adoption of Autonomous vehicles, Id imagine we'll be able to 3D print organs that wont encounter rejection. Alternatively, you could always take a medical holiday to China.

This has already happened there has been a huge decline in available donor organs due to reduced road fatalities, especially the kind that still leave organs viable for harvesting.

Perhaps a not so serious answer, but Larry Niven has a number of science fiction stories based on this concept, which is dubbed organlegging [0]. The one that sticks out in my mind is The Jigsaw Man [1].

[0] https://en.wikipedia.org/wiki/Organlegging [1] https://en.wikipedia.org/wiki/The_Jigsaw_Man

Interesting question, though I'd want to know what the breakdown for organ sourcing is before I consider what the impact would be.

i would assume that it would be a majority of the donations, i cant think of other ways people die where their organs could still be utilized? (drug OD // old age // etc)

Yeah, I wouldn't be surprised that it's a major source as well.

Looks like drug overdose is a significant (and unfortunately increasing) source:

http://www.npr.org/sections/health-shots/2016/10/14/49779944...

Looks like suicide is significant as well, though I'm not sure how to interpret this section of Wikipedia:

https://en.wikipedia.org/wiki/Organ_donation#Suicide

Crikey. What a morbid subject. :/

I would think that organs that are harvested from OD victims would not be "good" because of the harm that the drugs can cause the organs?

Perhaps its organs that were not effected // deemed usable.

From the NPR article:

Dr. Jay Fishman, associate director of [Boston's Mass General] transplant center, says an organ from someone who used drugs is not necessarily risky and may even be healthier than other options.

"You have to remember that as awful as this outbreak is, these are younger people who are dying, often with needles in their arms, and many of them were first-time drug users," Fishman says. "They weren't all addicts."

It's already been that way since safety belts became mandatory - the number of organs for available for transplant plummeted.

We can make organ donation an opt-out checkbox.

But the question is when would they donate their organs? (Making the assumption that most organ donations come from people in car accidents).

i dont see why you would not want to be an organ donor, body is just a rental anyway?

Religious beliefs, cryonics. (But then I repeat myself...)

I think the parents point is that we have seen in some places (Netherlands?) that a dramatic increase in organ donors happened when they switched from opt-in to opt-out.

In Portugal we have opt-out, while here in Germany it is opt-in, I never understood the decision, exactly because of what you mention.