If we're sharing anecdotes, I only got bullied after school or at the bus stop, never on the bus (at least there's an adult on the bus - usually none at the bus stops).

I think the bussing is avoided simply because it's a chicken/egg problem - if an significant number of parents don't opt-in, then they can't service the populace at large. In my kids current district they only bus between schools - if you live > 1mi from a school, you might as well walk/drive.