You should try Arizona in the summer next time you're in the USA - we have instant hot water 24/7 - even our cold water is hot.

Yes - I'm serious. In the summertime, our water from the "cold side" is typically luke-warmish at best. From the hot side, we can actually turn the temperature down on our water heaters and save some money.

It gets a bit better during "winter" (in quotes because right now, the temperature is around 32C - yep, shorts weather in the middle of November!).

Anyhow - you can purchase the tankless circulation system you describe, but it isn't cheap so you only usually see it on new houses, and only as an upgrade. Retrofitting old houses just isn't really possible without a complete interior teardown. The only other option is tankless water heaters, but those require a decent electrical circuit to each sink. So, most of us just have the central water heater tank, and when we want hot water, we turn it on and let it run (ain't like the water is going to disappear, thanks to the "water cycle"). Or we deal with the cold water (except here in Arizona - where again, our cold water is warm).

Electricity and gas are relatively expensive in Australia compared Europe or US, so I’m lead to believe. Might be better in a new house with good insulation on the pipes.