Brakes are cheap and pretty easy to replace (really) diy. Once your pads wear out, the backing plate will be pressed into the rotor, which will warp the rotor. Rotors are cheap too ($20-$50 each) and easy to replace, so it’s not a huge deal if you warp them, but it’s not something you should aspire to do.

Also, shops lie about brakepad life all the time, but maybe yours really are at 2mm, which is definitely worth replacing like 6 months ago. Also, your car does most of its braking with the front wheels anyway.

In conclusion,