Really? I figured most ovens had a self-cleaning option... I did this trick to recondition several cast iron pans and it works great, but be prepared for massive amounts of greasy smoke.
Couldn't find statistics on this with a quick search...
But yes, it is just an element that can go hotter and a shell that can withstand it. Ovens are incredibly overpriced for how rudimentary they are IMO. Ripe for 'disruption' if you had something non-bullshit to compete on but price - sizing is already standardised.
The cleaning module of the one oven I'm aware of that had that option was more than just a heating thing. The manual talked about foam and how to refill it. Different countries, different mechanisms I assume.