A couple other things....
Walking to the end of your street with other kids and parents is not the same as crossing streets in an urban setting. If my 6 yr old had to cross a busy intersection to get to her bus stop she wouldn't be doing it without adults or a crossing guard.
A 6 year old needs more supervision than just a 10 yr old. I'm pretty sure I'm in the majority with this. 10 yr old is different. Heck I was out bike riding the town at 10.
Also....asbestos, lead paint and no seatbelts were once seen as safe in the 70s.
Also...laws are even more conservative. In most states you need adult supervision until 12-13.
Asbestos etc was always dangerous. Walking to school is no more dangerous now than it was back then.
Its ridiculous that someone aged 10 can't walk to school. I bet it has more to do with car culture people will drive half a mile to the shop instead of walking - unless you have work to go to afterwards you should walk your kids 1/2 mile to school but most people take the car esp I imagine America.