Our school district has additional busing criteria than just distance to the school.
If you are going to a school other than your "home school", because of the "No Child Left Behind Act" (i.e., your home school is a low-performing school), you get a bus ride.
If you are part of the VEEP (Voluntary Ethnic Enrollment Program), or you attend a "magnet school", you get a bus ride.
If you have an IEP, you get a bus ride, no matter how close you live to the school.
If you attend your "home school", and do not have an IEP, you provide your own transportation, no matter your distance to the school. My kids attend their "home school". We are about 1 mile from the elementary school. It's not that far, but too far for the little ones to walk home.
My kids are lucky that the middle school is 2 blocks away and the high school is about a 10 minute walk. There are some students in our home school who live as far as 3-4 miles from school who also have to provide their own transportation. I often see them walking home after school when I'm out running errands. It's a long walk for some after spending the entire day at school.