I used to walk or take the bus, even in elementary school. I am not sure at what point parents decided they must take their kids to school. We did have parents dropping kids off and it was busy but not like it is now. I know then, at least to me, there was a sort of an air about about seeing kids being picked up or dropped off because they didn't have to ride the bus. Maybe that's it, parents gave in to not wanting their kids to feel less about themselves because they had to ride the bus?