Everyone in the uk has a central hot water heater, and nobody has a hot-water plumbed dishwasher. Presumably the 230V supply is enough to heat the water up quickly.

Do you also have hot water plumbed washing machines?

In the US, yes washing machines are generally connected to both hot and cold water. Unlike dishwashers which need to get even hotter than hot water, washing machines generally don't have any internal heating element at all.