No way could a bus turn around on our cul-de-sac!!!
You have to remember that busses are nearly twice as long as the Gas trucks!
(A large fire truck would be a special case, not a daily occurance)
And, no way could the bus be insured of being able to turn around on private property. Cars could be parked there, or whatever. Also, the bus company could be held liable for any intrusion on to private property. Even the OP's. What if it damaged a vehicle, or landscaping, trying to maneuver.
I am so sorry that the OP is in the situation of having to walk/drive her child to the bus stop. that is unfortunate, but is the harsh reality. The same reason that the OP probably enjoys living where she does, away from main roads and traffic, is the very reason that she is in this situation.
I drive my DS to school every single morning. And it is not because the bus could never come down to my house. It is because the freaking bus runs at the crack of dawn, nearly a full hour before I have to get DS to school.

(They corral the kids into the gym every morning until all the teachers arrive and the bell rings)