Some of them "NEED" special training. I expect "city drivers" for the most part.
Over here in the hills of VT we are soon to get the new FWD mail trucks. 80% of the roads are gravel. 40% of the year is snow or ice with a good portion wet or real mud. Small Jeeps are the preferred vehicle. My mailman is going on 350K on his. When the Chinese start shipping parts for the new mail trucks we will get then here. With most mailmen questioning the validity of the new trucks as being unsuitable and incapable of getting around in the hills, the PO states you can keep your old vehicle as backup. Maybe we will see these new furrin made mail vehicles 3 or 4 months of the year. FWIW the postal rules are made in Atlanta GA for what the whole country needs. That seems to be tire selection as well.
I think the drivers around the whole country know how their RHD vehicles work.