For those that know why...
This is eating at me...
There's a lot to be learned just from looking at the pictures, and several have pointed out the clues already.
Serious heat went into those rotors, especially since supposedly only 100 miles went on the car...
What's the first rule of a brake job?
Right, test drive... I'm of the opinion that the "professional garage" didn't do this, or failed at their evaluation, if ANYBODY gets sued, that's the place IMO.
The deep grooves on the inside of that caliper are telling a different story, and certainly not one of immediately pulling over during that test drive.
Broken caliper bolts??
We're they properly torqued to 120-130lb-ft?
Red loc-tite?
Maybe an improper bedding job gone horribly wrong?
Ceramic pads are indeed hard, and can be difficult to bed properly, especially on used rotors, but that heat checking is worse than my Standing Mile rotors that I burned up, and looks as bad as this rotor from this test we did!
This is what a rotor that ran ceramic pads (Z23s) in a Standing Mile, for approximately 30 passes, looks like. ~175 to 30mph at .5-.7gs deceleration.
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This is a simulation of
@TrackDay at Brainerd on the brake dyno, and what the rotor looked like afterwards. (The dyno can't accelerate as fast as our cars, but braking is reasonably accurate)
This is the kind of energy that this rotor took, (and the caliper and mounting hardware), and further, the dyno mounting bracket (reasons) is actually LESS stout than our car.