While you don’t do motorway driving as part of a basic test you do get to do plenty of dual carriageway lessons. I certainly didn’t find my motorway lessons to be greatly different from dual carriageway lessons except that there were more lanes and I was taught about exiting/joining the roads and how to navigate by junction numbers. The actual rules about overtaking and lane-hogging were identical, except you could be overtaking two lanes of traffic instead of one.

I’d suggest that, even though it’s good practice, most people don’t drive like that is because (in the UK at least) most people are never taught to drive on motorways. You can’t drive on them before you pass your test and unless you have a special offer as I did most people stop learning what to do from that point on.