I'm just shy of 100K miles on my 2018 Ram 2500 and I'm still on the original set of brakes. 90% of those miles are towing my 25" enclosed car hauler so those miles are with a 9-10K lb load. You've got to love the exhaust brake on that truck.
That being said, $1,700 seems a bit high, even with a new set of calipers. They're not THAT much. I just had the rear brakes replaced on my Porsche and with 2 rotors, 2 sets of pads, and 2 sets of electronic rear sensors to tell you when the brakes are down to a few mm of thickness the cost was only $953. I would have done them myself but the car has an electric E-brake and I don't have the scan tool needed to disengage the E-brake for servicing. It's a $400 tool and I probably won't need rear brakes again before I sell it. If I decide to keep it longer I may buy the tool if it works on the Porsche I replace it with.