You are partially correct when you cite only 2 training facilities
Most RV makers also "Factory Train" but only in their product line.. Same of Auto makers.. You can go to mechanics school. or you can go to say GM Factory training.. But the GM school does not teach Ford (And the reverse is also true)
Both however teach the concepts needed to cross diagnose.
I've had general training, And verley likely could (per my brother who did) pass the certification test.. If I choose to take it.. But since I choose a desk job over a grease job.... I did not choose to take it.