I have no idea how widespread it is - but the place I bought my TT charges $155 per hour labor. They get $90 from Forest River they get less from some other RV manufacturers. I also understand Dometic pays $87.50 no matter what make of trailer the faulty component is installed in.
Another thing. I had my Suburban furnace repaired 10 months ago, it was done under an ExtraRide Extended Warranty which the dealership sold to me. Those repairs were done at $80 per hour for labor.
I've also heard that some manufacturers are trying to go to the automobile labor standards.
If your transmission fails and has to be replaced under warranty from Ford, Chevy, Dodge - the book list X hours for labor for the repair/ replacement. That is what the car dealership gets for the repair, no more, no less. How many hours work is actually done has no bearing on how much the dealership gets paid under warranty.
So of course, the dealership shop foreman urges his workers to speed up, cut corners is possible, all to make a 4 hour repair take 3 hours.