Maybe it sounds fancier than it is? Is not like it has a little robot that cleans the oven. It's just a mode where the oven can get the internal temperature very high (up to 1000 degrees F according to that article) that just incinerates any organic material stuck to the oven walls.
Most ovens in the U.S. burn natural gas, which burns at 1000 degrees F (which is the self-cleaning temperature).
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.
Or just use easy off which is a spray on acid.
Edit: because of course I triggered a storm. Maybe it's common elsewhere. I've lived in few EU countries, rented then owned a few houses, exactly only one of them had an oven with the self cleaning(by heating up to like 500C) feature, I don't think we ever used it. When we bought our current oven none of the ones we looked at had that function. A fancy Candy we looked at had a function where it cleans itself with steam(where you fill up a provided container with water and then it heats it up to fill the oven with steam and in theory that softens the gunk. No idea if that actually works).
If it's common where you live, then my apologies for this comment.