I'm pretty comfortable, now, with my son (14) riding in the streets, even by himself. But it is dangerous, you just listed a bunch of reasons why.
A. now has a couple years of street education riding with me. That's with me saying -- look at that car, he could make that left in front of us without signaling -- see how far these car doors open?, that's the door zone -- let this car go through the intersection ahead of us, we don't want the surprise right turn -- and so on.
And, #1, awesome.