The people of the state do not have the right to decide who drives school busses?
States have no rights at all. All of their powers are derived from the people. And the people may not confer any power to the states OR the feds that they do not first posess.
States have the power to do certain things. Do I believe there should be traffic lights? Yes. Do they violate rights? Not really. They merely automate that which would be required under the common law.
Have you ever been to any rural towns? I have. I've been to places so rural that there were almost no signs or traffic lights anywhere and there was ONE sheriff and a deputy for the entire town. How did people determine whose turn it was to proceed through intersections with no traffic signs or lights?
Speed limits are another matter. I oppose them and believe they violate rights.
If states can regulate the speed you drive then can they also regulate the number of times you chew your food before swallowing?