In the old days, brake rotors used to be relatively thick. They did not warp easily, and if you ran your brake pads down to metal all you needed to do was turn the rotors to smooth them out and you were good to go.
These days, many cars have very thin rotors, so that they can shave every last ounce of weight off of the car (as well as every fraction of a cent in metal cost). They warp more easily if you are hard on the brakes, and if you wear your pads down to metal you’ll gouge the rotors bad enough that they won’t be able to be turned and still be within spec for how thick they need to be to be functional.
So, your mechanic isn’t necessarily ripping you off.
However, even with today’s thinner rotors, it’s still very unusual to need new ones with every brake change, unless you are doing something unusual. 83,000 miles is a very long way to go on a single set of brake pads unless you do a lot of highway driving with very little braking. Most cars are set up with little metal tabs on the brake pads. When you wear the pads down far enough the tab will scrape and make a noise. If you don’t change the pads then, you run the risk of wearing the pads completely down to metal, at which point they gouge the rotors.
Do your brakes pulse when you step on them? If you do a lot of hard stopping (long hills, city traffic, etc) then all of that heat generated could cause the rotors to warp.
If the rotors are gouged, the brakes will usually work fine with new pads, but you will wear through the pads VERY quickly, and possibly unevenly. The right side might wear significantly faster than the left, for example. If the rotors are warped, your brakes may feel like they are pulsing, and the car may want to pull towards one side whenever you brake.
Since bad rotors will very quickly damage new brake pads, most mechanics aren’t going to honor the warranty on new pads if the mechanics says you need new rotors and you don’t replace or turn them.
As I said though, needing both new pads and new rotors every time you go to the shop is unusual. You should go through many sets of pads before you need new rotors. If you aren’t gouging or warping the rotors, it might be time to find a new brake shop.
ETA: If you don’t know what you are looking for, rotor damage may not be all that visible if you are just looking at the rotors. Run your hand over the surface of the rotors. If you feel grooves, then they are gouged and you need to turn or replace them. You can usually feel warped rotors when you apply the brakes. The brakes will either pulse or pull the car to one side (note - other things can also make a car pull to the side, not just warped rotors). Just looking at the rotors isn’t a good test.
