I can understand “coach” to be a vehicle type, but not one that is named in the law in areas where I edit, it is a class like “SUV” or “van” or “convertible”. The legal term around here is “bus”, it means a vehicle with more than x seats (8 I think) for the transport of people. Maybe there are more and different vehicle types elsewhere (minibus?).
I meant so say what is written on the wiki pages you cited and it is also what I wrote there in 2011: Key:tourist bus - OpenStreetMap Wiki