It's an evolutionary advantage for the entire herd when a single injured member is incapacitated, thereby allowing predators to focus on the injured member instead of healthy members of the herd.
So by basically erasing all hope for recovery for the spinal injury victim, Evolution has enabled the non-injured humans a means of escape from lions, tigers, and bears.
Since we live in modern society, it's uncommon to see this kind of pursuit. However, evolutionarily speaking, the movement to cities and civilization is a pretty recent phenomenon. Until that fateful event, humans were preyed upon by many other wild animals.
You're correct, but only if that single injured member was impossible to save. Saving lives is also a part of evolutionary effects, as it further aids reproduction chances of the organism. Evolution is the extended arm of relativity, and evolution is solely based on individual vs. environment. Not smart vs. dumb, or ugly vs. beautiful, or strong vs. weak. It cannot be rightfully explained in any other way than that the organism which is best fitted to its environment will have the best chances of reproduction. If being saved is a real possibility then this factor is also included in the equation of evolution.
It is true that ultimately drugs (medicine) will end up removing our own built in abilities of coping with reality as those who are born with a complete lack of this mechanism also reproduce with the rest. This is however not to be feared because reality for us now is not what the reality for us was when we were in the jungle. So it would be a real slap in the face to evolution to say that we're "messing" with it, because you'd be so ignorant to think that you can control evolution. It is only a product of reality, it is only a product of relativity. You can't cheat evolution.
It all comes down to two opposing theories, fate vs. free will. It is very controversial to say that there is such a thing as fate, as it is usually associated with nonsensical TV-shows about anything from clarvoyants to fundamentalists (e.g. doomsday). However it seems that we tend to wish for the absence of fate and that we are in control of ourselves and our lives -- but then one has to question if this doesn't cloud our judgement of the truth. There is also the argument that if fate is "proven" then we would all just lie down and wait for death. The problem with this argument is that once again one makes the fatal assumption that all humans would be susceptible to this and that all humans would embrace it -- but without pointing any fingers I think we can conclude that even if you present the hardest evidence -- there are still many people who would deny it. This would then be another product of fate, that in return coexists with our existance, rather than our annihilation.
I think this is an effect of relativity and the fact that many people don't tend to accept proof of what they, with all their hearts, wish for is untrue further also becomes an effect of fate. What I'm trying to say is that even if fate is proven to exist, it wouldn't make a difference, as those who accept it and go down with it will die, those who accept yet ignore it and those who won't accept it will live on. And in evolutionary terms this would then lead to offspring less likely to go down with this "truth". Perhaps genetic, perhaps due to "alternative education." We would never accept murder or rape or genocide as an inevitable effect of the universe. If we do that, we're no longer what we consider human. We would be equal rocks, or water, the sun, or the moon. Peers with our futures written on our foreheads.
Then again -- as the uncertainty principle shows us -- we can never be sure of this. And if you think about it -- this is deeply rooted in our very definition of life itself -- uncertainty.