There is no negligence in split second reactions. Situations on the road change rapidly. Instinct has the biggest influence on your reaction. It is instict to avoid a deer. When you have to go into a thought process of deciding which way to turn to avoid the deer, then it takes too much time to do so thus it becomes an accident. Accidents are unintended. I doubt any one who swerves to miss a deer intends to hit a car instead.
Because they have failed to use their noggin to think such scenarios thru ahead of time. They have become lazy drivers that think it is just as natural and comfortable as walking. They have forgotten the inherent risks associated and the amount of responsibility they carry when driving. Our laws and society has allowed it to happen.