Rear view mirrors were a matter of good logic and had nothing to do with Federal Mandates.
In regards to seat belts you might be surprised to know that many people that owned early model cars tied themselves to their seats for fear of falling out when bouncing around on improvised roads - a logical device that the human innovation stumbled upon to protect themselves while driving. Children groceries and even adults were either held or strapped to various improvised points which was the precursor to seat belts.
As cars improved those belts (usually ropes) were discontinued. I recall my own parents using ropes to keep grocery bags from tipping over.
Look at the sign on your outside rear view mirror. That is a federal mandate. So are the seat belts and air bags. The pedals too, I suspect, after the recent accidents of drivers confusing them. Bumpers of course. Windshields. Dozens if not hundreds of other things, baby seats among them. The products we buy are regulated by the Feds and by the states, there is no escaping regulation, supervision by Big Brother, even when buying cheap children’s toys in Chinatown. Are traffic lights, their sizes, brightness, positioning not regulated? Are lanes paintings on the roads, interstate, state, county, not regulated? What’s not regulated when you get in a car and drive away? And to be safe on the road, that’s what you and everyone else want, silly uninformed libertarian protestations notwithstanding!