>Tamar's kids have to go through stops 2 - 7 to get off at school. The return route is stop7 - stop1 for home. The kids who got on at stop6 only have one stop each way.

Not necessarily. The buses usually cover one area each and zig-zag through it, so if the farthest out is 10 miles, the nearest shouldn't be more than 7. And then there usually aren't too many good options to make routes reversible - there are a lot of places where a right turn is easy and a left turn from the opposite direction would take a longer wait, or there are one-way streets, so the bus drivers usually don't reverse their routes.

My daughters have used probably a dozen different bus lines over the years (moving, changing schools, schedules got changed etc) and it was always in the same direction. Maybe we just had such luck, but I figure that this mostly is the case.