Why don’t cars have bouncy seats like coaches? Look really comfy.
Suppose the average car user is only in it for probably less than an hour, rather than doing 9 or 10 hours driving a day.
Not got as much room around you in a car for bouncing up and down, side to side and that.
You’d have to stick air compressors and tanks on the car for it. Trucks and busses need air for the brakes and suspension, so it’s already there.
A more useful truck/bus thing to stick in cars would be a night heater, so you can get it lovely and warm before you get in on a cold winter day.