I had an extremely liberal english teacher last year, who discussed this with me. She would agree with you. I agree with you up to a certain point; however, my geometry teacher has more wisdom than I give him credit for, and he said this,"There is always a way to game the system, this is just one way. It's not a problem as I have no point in stopping this." It was part of a larger conversation in response to online tests.I can assure you, I do not approve of eugenics, which is (to my understanding) basically having a "master race" (i.e. there should only be cis-white humans, and we could probably go more in detail).
I just think there is priorities. Children, they have their whole life in front of them. Old people have very little left ahead of them, and what they have ahead of them, no offence, is unlikely to ever benefit anyone ever.
As for the physically able thing, which I assume is what you are on about.
If there are two children one has Cystic Fibrosis, and one had no physical ailments. They are both in a car crash, and both need a new kidney. There is one possible donor, which means one child would die. The child with Cystic Fibrosis has a shorter life expectancy, due to their disease, than the child that doesn't, and one can assume that they will experience mild discomfort (at best) for at least part of their life.
So in this scenario, if the doctors were in charge of the decisions (due to the health care system being government owned, and not privatized) then they should, in my mind, take that into consideration, and unless the "healthy" child has a much lower chance of survival, then they shouldn't "waste" that kidney.
If the health care system is private, then whoever pays the most wins, I wouldn't be able to change that, even if I ruled the world
To tie this together, I would support having the healthy child getting the kidney, but, if the child with cystic fibrosis can pay for the kidney and stop the healthy child from getting it, so be it. There is no point in stopping it. We would be better served to using that money gotten from the kidney to fund research for other medical things, such as what @Strikingwolf was talking about.
There will always be a way to "game the system".
I really wish more research and funding was put into genetic manipulation and other cloning.
(Don't really know much about that subject, sorry if a lot of money is being used to fund those two agenda)