Home oven over 500°F?
They do go above 550F, it's a question of design and the type of wiring used in an oven. THWN is commonly used to wire up home ovens, which has a maximum surrounding ambient temperature rating of 105 degrees celsius. 

So, oven makers need to design ovens where the ambient temperature of things outside of the insulated oven cavity don't reach a temperature above 220 degrees fahrenheit (that's where the wiring lives), and not exceed the insulation around the door of the oven, and not burn anyone coming in contact with the sides. 

So it's both safety and technical cost reasons. Hotter home ovens are possible, and available, but they're made a bit differently and the cost to produce them is a bit higher. Since most people cooking at home don't need something that goes north of 500 degrees, there isn't a big market for them - and the market that does exist is mostly in the commercial space. 

A residential implementation would have some pretty specific insulation requirements, be slightly larger than most home builders anticipated (making them harder to install) and naturally quite a bit more expensive and scarce.