Only the british have ass-backwards sinks with cold water coming from one side and hot water from the other, burning your left hand and freezing your right hand.
https://www.youtube.com/watch?v=HfHgUu_8KgABecause our hot water traditionally comes from tanks, which can become stagnant or polluted. Whereas cold water comes straight from the mains, and is regulated.
There's not much necessity to have the water mixed though. Cold water is just as effective as hot water when it comes to washing hands. If you prefer warm water, you just adjust how much comes through until it's cool enough.
Alternatively, you plug the sink, and fill it with both until you get water you like, then wash with that.
Although mixers are becoming common and popular.
BUt that points not overly relevant to your discussion though, as Britain predominantly does not use bidets. That's a European thing really.
