Late to the discussion but my 2018 JCW brake wear light came on. At around 15K miles. Caught me by surprise. My usage is easy on brakes. I usually get 50K miles or more. With one car (Porsche Turbo) I managed around 124K miles from the front brakes. Rear brakes were worn but no warning light on when I sold the car at 161K miles.
Turns out the JCW's driver's side rear brake and one pad -- the one with the sensor -- was worn down.
After the pads/rotors/sensors replaced I noticed the the stability control symbol flashing during a sweeping right hand turn. And I could feel the driver's side rear brake being applied. I tried taking this at lower and lower speeds. The stability control still applied that brake.
Decided to try a brake fluid flush/bleed. Had this done and after the stability control system was quiet. Oh with some effort I could cause it to activate but then its intervention was justified.