Or a heat pump dishwasher? If he finds a way to turn a heat pump into lighting he's got it made.

Radiative heating is (relatively) common in the US too, although not so much in new builds.

That used to be more common in the us. However forced air is more efficient (at least traditionally, not sure what the latest is) and most importantly allows for cooling which is needed when the summer gets as warm as the us normally does.

Hot water heat is extremely common in the Northeast US, at least. Not universal, but very common. It circulates separately from the drinking water but is heated by the same machine.

Different in australia too. Places with warmer climes tend to seperate these things.

I know why, but i'm still surprised at the dearth of reverse cycle outside of Australia. Incredibly ubiquitous here.

Space heater in the US refers to something different.

Home heating may be done using steam in radiators. As far as I'm aware this is most common in older buildings or in the north. New York has district heating that seems to resemble district heating found in parts of Europe.

A space heater in the US is a resistive electrical heater, that isn't usually connected to the main heating system for the home. Typically these are small portable units, and they're used to heat just the room they're put in. Your thermostat might control several rooms, but you might not intend to be in those, and night not want to pay to heat all of them. Or it's unusually cold, so you use a space heater and just stay in that room.

In some special circumstances, yes. But I also have one of these air to water heat pumps and it is entirely off during half of the year or more as the much cheaper solar-termal tubes on my roof cover all the hot water needs (and use the same water tank). I was expecting to be able to use the cold air and installed special openings in the cold air duct, but in the five years or so since I installed the heat pump I never even once had the opportunity to do so.

It puts out cold air to warm the water, instead of generating heat. Temperature control is just moving heat around.

I have a heat pump water heater that's vented to the outside and I call it my outdoor air conditioner, it's so nice to stand under the vent on a hot day and get cold AC on my neck.