Truth there.
I've hit 3 elk and 4 deer, I shot 4 of those before I called CSP and in not one case did the CSP have any issue with that. I kept 1 of the elk (yes I got a carcass tag). I have shot two other deer that other motorists have hit, and again, LE (one deputy and one City) had no issue with it.
I would never leave a wounded animal. If I could not safely dispatch it, I would wait for an official to arrive.
Also realize that there are laws and such. Leaving an animal, dead or alive, on a highway without taking reasonable steps to safeguard other motorists can get you in trouble. I have done 3 vehicle accident reconstructions involving a secondary vehicle hitting a wounded animal and those were messy cases. One resulted in a fatality and another a young man who ended up being in a vegetative state for the rest of his life. Court cases and verdicts against the driver who initially struck the animals did occur.