I've worked on many domestic and foreign cars, and I've never seen slide-out calipers. Most have a window so you can check pad and rotor thickness, but none have a slide-out section.

Even if you don't replace the rotor, you still have to remove have it turned (grinding the contact surfaces flat again), so the new pads make good contact, instead of being pressed against the ridges and valleys left in the rotor from the worn-out pad.

It just seems like a bit of over-engineering.

It isn't over-engineering because they are just Brembo calipers with Telsa stamped on them. Brembo has a huge share of the performance/racing brake market.

On a regular car you might have to have your rotors turned, but on something like this the rotors are more heavy duty and I think resist warping. Plus, on something like this you could run a lot softer pad (for track days) and need to change them out after a single weekend of use. It is still a good idea to sand the rotor surface, by hand, just so the pads will seat correctly.

Edit: And I do agree, I've never seen a "normal" car with the slide out pads... although they always look like you can do that until you get close and realize it is going to be a little more work than you thought. :)

This isn't quite my field, but I've been told you only need to have a rotor turned if it's warped or scored; otherwise you can just change out the pads, then apply the brakes heavily to conform them to the rotor surface.

That's exactly what I have always done.

I've never seen brake pads wear out without scoring the rotor.

Some pads have a thin piece of soft spring steel that drag on the rotor when the pad is thin, producing horrible screeching noises without damaging the surface.

Almost all performance brakes have this easy drop in pads to make changes faster at the track (I'd change pads 2-3x a track day in my evo). They bought an off the shelf brake setup from brembo. Nothing special here for people in the know.