Search around and you'll find a couple of posts from me from the past whining about how my front brake rotors are always rusting up because (1) I don't drive my car much, and (2) when I do, I don't use the brakes very much/very hard.
To try to solve this, I actually got in the habit of trying to clean the rotors off by stopping pretty hard ... on those rare occasions that I
do have to do "normal" braking.
But the rust apparently got further ahead than the pads could scrub clean, and the result is I've now worn the pads down to the wear indicator on the rough rotors!
Here's what they look like now:
Makes me think that cars with regenerative braking will have the same problem - possibly more than regular cars.
These may still be OK to be machined down; I haven't looked into it yet.