KIA replaced my front rotors and brake pads Aug 2014. One year later my brakes were not functioning well and KIA said the right front rotor was grooved because of rust and should be replaced, adding I should do both to keep them even and change pads, which were hardly worn. Are they ripping me off? My car sits outside in a plastic temple garage. I live in 4 seasons - winter lots of snow, summer can be very humid for a couple of weeks. I do not drive my car often as I'm retired. Can non-use speed up rusting of rotors?
Take the car somewhere else for another opinion, as it sounds like this particular KIA dealership is trying to pull a scam. Pads typically last 30,000-80,000 miles depending on driving style, pad type, etc. So, replacing the brakes every year is not typical, especially with limited driving.
Surface rust can appear on the rotors if they sit for a while, but this goes away after using the brakes a few times and does not impact pad/rotor life in any significant way.
If you had problem in right front tire, when you brake, the car would pull to left or you would have uneven braking marks if you brake so hard that tires slip on asphalt. You can test this easily.
In either case, your problem is probably something else but the repair shop puts some extra work. Because you need to lose a chunk of your rotor for rust to make an effect. There are rotors full of holes to help cooling. If tiny holes made so big difference, they wouldn't work at all.
I would try to get an opinion from another repair shop.