Rear view cameras?

At this point I think the only place they would be practical
would be Trucks that always keep the same trailer.

They would be stolen or broken off trailers that get left in yards.
The lense would get dirty just like the back doors do, drivers
would clean them improperly scratching them up and makeing
the picture blury.

The back of the trailer has the roughest ride, with the current RV
cameras out there they would not last very long because of that.

Owner operators with their own trailers could use them for a while
but they are usually experiance enough they would not buy them.