Maybe it's styropyro's house?

In the US, most protection comes from the breaker. It's not common (or at least, not standard) to have overcurrent protection on extension cords, power strips, or even the outlet itself. And for typical wiring and uses, it usually works well enough. But it is possible to connect a space heater or hairdryer (1500w and 1800w respectively, due to the 80% rule for continuous draw) to that standard 16-gauge extension cord, or connect multiple space heaters to one circuit. Some homes are wired.... Creatively.... Making it easy to do. In these cases, you're relying on the 15-amp breaker to trip, which would happen quickly. Not quite as quick, but still happens on a 20-amp. But it might melt a 15-amp receptacle first

If it's a 30-amp circuit, it won't trip at all, unless the outlet melts to a short. And this is all assuming the wiring in the wall is rated for that amperage, which is implied but not stated. There are certainly a number of stories where someone upgraded the breaker to keep it from tripping, but didn't upgrade the wiring.

If we assume he's talking about the wiring in the wall, this gets very simple. I once lived in a place where the upstairs bedroom and downstairs living room were on the same circuit. I currently live somewhere where a single circuit controls ALL of the bathroom outlets (multiple bathrooms), the garage, as well as outside outlets. Apparently GFCI outlets were more expensive than the entire mess of running copper all over the place.

what’s he running that’s goong to melt those wires?

500A on a 110V (220V?) main is a lot of W.

Well for starters most residential outlets are rated for 15 amps. You don't need to run a lot of stuff on that outlet, a vacuum and a space heater is most likely enough for the outlet to overheat. Toss in an extension cord and another appliance and the outlet is going to melt. And since you're only pulling like 25 amps once the short happens when the live parts touch each other the arc explosion would be spectacular. Since you're on a 500 amp switch gear breaker with selective coordination set in a way that not only is the outlet done, but the wiring I'm assuming is not ran to the outlet in 600kcm copper, so all the wiring from the outlet to the breaker is also going up in vapor. By the time the breaker trips your house just went through a neat fireworks show and it's ablaze.