Why Are There Inside Rear View Mirrors In Class C's

I have a rear window on my coach. Therefore needs a rear view mirror!

Those van chassis' come off an assembly line. 'Then' the coach builders get them. Some RV models have back windows some do not.

I know I would have been bummed out if my RV had no rear view mirror!

Since I usually have the shades down in the back I don't use it BUT I do turn it to the side and it gives me an additional view of the road on that side. I know not the cars because so high but it does show the trucks.