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.