Why can't the plumber fix my kitchen sink?
Plumbers don't have x-ray eyes, sometimes they need to scope a pipe to find the problem. This does not make him a bad/lazy plumber. It just means he doesn't carry the scope in his truck, or the company has a special technician, who is the only one who runs the camera. Let the company scope the drain so they can see what they are dealing with, at which time they will offer you options on how to correct the problem.

It could be:


A ball of roots, that could not be broken up by the auger.  
A collapsed pipe.
A shifted pipe.
A large foreign object that cannot be moved by the auger.