I think many of us must have had sad but unavoidable experiences like this. I recall having hit both
Rabbits and birds over the years and also birds that have flown directly in front of the car (the nearest miss was a Common Buzzard .... now that did appear BIG in front of the windscreen).
However, I have also rescued a few in the past, most recently and notably a very young Snipe in the Scottish Highlands last year. Mind you, he would probably have been safe as it was one of those roads where you do not see another car for hours!
What is inexcusable is those instances where road kills are the result of deliberate actions by those morons who think that there is some fun to be had by killing wildlife that way. Many years ago I saw a "boy racer" (the polite term for this individual) deliberately speed up and drive directly at a feral pigeon in Princes Street in Edinburgh. The bird did not stand a chance and all we could do was to move the dead body to the side of the road to avoid the further indignity of it being shredded in to little pieces.
Richard