Houses are wired for 16A per circuit on both sides of the pond, with high-power appliances typically pulling around 10A to avoid tripping the fuse when something else is turned on at the same time. It's just a nice point where wires are easy to handle, plugs are compact, and everything is relatively cheap.

The US could have toasters and hair dryers that work as well as European ones if everything was wired for 32A, but you only do that for porch heaters or electric vehicle chargers.