Why Is It?

Why is it people drive with their handicapped placard hanging from the mirror? It obstructs visibility and clearly states that it should be removed when driving.
Why is it that people litter? Can't they just keep the trash in their car until they get to their destination? Why do they throw out burning cigarettes (don't even know how to spell it!) when there is fire danger?
And, last on my mind today, why don't people pull over and/or stop when an ambulance/aide car approaches? What if it was their family or friends inside?
I just don't get any of these things!