Unfortunately, we just don't live in a safe society....so what might work for one area will not work for another.
Gosh, I used to walk a mile home alone in KG....that would be unheard of now and alone would be ever so risky.
I'm with you on allowing freedom and creating independence. Can she walk home with a buddy and you wait outside your home so you can see her and friend walking together?
And has she asked to start walking alone or to a friends?
I recommend she's at least in the 5th grade before going it alone.
And waiting in the car is a perfectly fine alternative to standing out in inclement weather...I would pay bills, make phone calls, listen to a favorite CD, catch up on reading....your car is a great, quiet place to catch a little solitude.
Also, these years go by so quickly, I would probably look at it as an opportunity to get to know the other families and kids and see what school and after school activities everyone is going to.