Whilst I detest the idea of sending a child to school at all, let alone one you don't want them to go to. I have to say that my youngest was going across town on two buses at 11 years, and he was one of the most naive kids I've known. It sparked off a lifelong interest in transport (perhaps a little sad, but he does now have a pilot's licence) and, by the time he was 18, thought nothing of jetting off around the world on his own.
I have also spent many years teaching teenagers with learning disabilities how to travel independently - something they relished and for which their parents were almost always grateful. Indeed, after they'd left school they would often stop me in town and tell me where they were en-route to or where they'd travelled to - on their own. We're talking youngsters here who you'd never have dreamed would ever go any further than the corner shop by themselves. As one mother said, 'I was having kittens until she appeared back at the end of the street, but you can't be around for them forever, can you?'
Also, whilst your daughter doesn't know anyone on the bus route at present, she may well find that once she starts then she will find others on it from the school. When I was a girl, I went to a grammar school across town and was one of just a couple in my area to go there. By the end of the first couple of weeks we discovered there were half a dozen of us who lived on the same route but had never met before, and we mostly used to all ride home together. In fact, one of them lived on my nan's bus route. Forty years on, we're still best mates.