I believe it's mostly due to not having always hot water hookups available where laundry would be or not consistently having hot water always available. (as in on demand, from a large boiler that wouldn't impact the remain of the hot water uses)
I agree it's more British than Argentinian. But "Argentina never one of the rulers" isn't quite right. There were several stints of Argentinan (or Spanish but back when that was the same thing) occupation long before the war.
Lol