In Canada, or Ontario at least, the AZ is for tractor trailers and some larger motor homes. For the motor homes equiped with air brakesDon't get me started on RV drivers, truckers have to test and have a CDL, RV's all you need is a license and may have never driven anything bigger than your Prius.
you could do the night class.
You used to be able to get an A license with a pick up truck and a trailer registered for a certain weight.
You could get the A with a pickup, take a night class for the air brake endorsement (Z) and go to work driving heavy trucks.
You can't do that any more. If you want the AZ you need to test in a tractor trailer with a manual transmission.
Now you need an AR for large RVs. A is the weight/vehicle factor, and the R is recreational.
Other RVs like C class are still just a regular driver license.
I might even argue there should be an endorsement for these super cars. Mclarens etc. They are beyond regular powered vehicles.
In the end I do not support regulating the hell out of everything so carry on I guess.
But I do like to know the guy coming at me with an 80 000# vehicle has some training. Same as the guy landing the airplane I'm in.