Originally Posted by csdf

[Mangled anecdote]British taps were, until recently, not allowed to be a single mixer unit because of the danger of the temperature being set too high and you scalding yourself when you weren't expecting it. If you have separate taps then (barring stupidity), that can be avoided. I think modern mixer units are supposed to have some sort of valve that stops you turning them on at maximum heat setting, or something. [/mangled anecdote]
The skill of quickly swapping your hands from hot to cold taps in order to get an average of "warm" is one of the defining features of being British, imo.