Yeah I've been thinking about the two taps thing with shower taps. For my shower tap, you turn it counterclockwise to get water running. Where it goes from slow flow rate and cold, to high flow rate and hot. I thought that it would make sense to have two knobs so that one controls flow rate and the other controls temperature. As it stands, one knob ambiguously controls both the temperature and flow rate of the water.
Two taps - one for cold and one for hot makes sense. Since they each control the flow rate of hot/cold respectively. And from what I understand, this matches with the internals as you have one pipe for cold water and one pipe for hot water. Of course, rich people probably have more complicated setups that allow for even more precision...
In Germany, the thing I'm familiar with is a small lever that you turn left/right to control the temperature and (depending on whether it's mounted horizontally or vertically) either up/down or to/fro to control the flow rate:
Two taps - one for cold and one for hot makes sense. Since they each control the flow rate of hot/cold respectively. And from what I understand, this matches with the internals as you have one pipe for cold water and one pipe for hot water. Of course, rich people probably have more complicated setups that allow for even more precision...