It's easy for us to sit back and criticize motorists, but the fact of the matter, is that many of these people have no choice.
Many, but not most. Bikes and walking for long distances are not good transportation solutions for a lot of elderly people or people with severe physical disabilities.
But I have less sympathy for the overweight 50-year-old who just thinks that exercise is for health clubs (that they don't go to) and not to be done on public roads.