Many of these laws were to prevent poaching. While working with Texas Game and Fish back in the early 60s there were a group of people in the South Texas area that would use an old junk vehicle to hit deer on purpose so they could take the meat. Even at that time it was against the law, we must have arrested a dozen or more for killing deer with a vehicle, usually a truck with a heavy brush guard type bumper. After a while, they got smart, would have one vehicle hit the deer, and a second one would stop and pick it up. This was also against the law. It is the same today, the dead deer along the side of the road belongs to the State of Texas, and there are no provisions for an act of mercy. However, if reported to the Game and Fish people in a timely manner, someone will come out and dispose of the deer and transport it for processing, the meat is then given to some organization that can use it such as the food bank, Salvation Army, etc. This does not happen very often due to the size of the state, the number of wardens available, and the fact that most accidents of this nature are not reported unless someone is injuried. Most often, the animal is left for the coyotes and vultures.
While I admit it is a waste of meat, it does prevent the crooks from taking game illegally, and there are a bunch of folks that would do just that, given the opportunity.