Rotors wearing excessively

In October of 2019, my vehicle failed inspection due to front brakes. We had the repair done, which included new rotors as well as pads. At the time, the mechanic said the rear brakes would need to be done soon as well. We got those done 4 months later (Feb 2020), and those also had to have new rotors. He said none of them could be turned. New brakes and turning of the rotors had been done elsewhere prior to this.

In July of this year, we were back at the mechanic because the brakes were grinding again. This trip required the new rotors to be turned, and the mechanic said he didn't know what caused it to need it so soon. He assured me it was not faulty parts or installation.

Now, here we are 4 months later, and the brakes are grinding again.

I have been driving for over 50 years. I don't ride my brakes, although we do live in a much more "hilly and curvy" place now. I've adjusted my speed so I don't have to over use the brakes. With this pandemic in full swing, I also don't drive nearly as much as I used to.

Any idea why these rotors are wearing out so soon/easily?