I have a different take on this. During summer break from college I drove a 7up truck in Atlantic City. I was always told to trust the mirrors and, for sure, you had to because not to meant you had to lean out of the cab with the door open. I had one problem tho. A cop parked his motorcycle directly behind my truck and I started to go in reverse. He came flying out of a store just in the neck of time. But you're right - proper mirror adjustment should take care of most probs plus using your own X-ray vision.
I'll digress here. I rounded a turn too fast in my above truck and lost a good bit of my load onto the road. Remember those little 7-up 7oz bottles. Indestructible. I lost only a few.