The reason motorways are called such is because they are built specifically for motor vehicles and no other road users. This is what distinguishes them from other roads. They are a recent phenomenon compared to the roads in this country, some of which have existed for thousands of years.
On any other road, the motorist is the only one who is there by license and not by right. Roads were built for pedestrians, carts, horses.
Anyone can use the roads - pedestrians, cyclists, horse riders, cart drivers, and those driving motor vehicles.
The difference between a driver and a cyclist, pedestrian, or horse rider is that the latter three have an inalienable right to be on that road. Anyone can walk on a road. Anyone can take a pedal bike onto a road.
If you want to take a car onto the road, you have to prove you are sufficiently competent, healthy, and make sure you are insured. Drivers do not have a right to be on the road: they have a license only and that can be removed.