In my experience (US), they seem to be uncommon in residential properties. I've seen them in many hotels, though.

Indeed this solution has been standard in much of Europe since (at least) the nineties.

It seems to have had slower uptake in the US. Donald Norman’s ”The Design of Everyday Things”, 2013 edition, contains this passage in a list of different faucet designs (p. 151):

> Control temperature and rate of flow. Use two separate controls, one for water temperature, the other for flow rate. (I have never encountered this solution.)

I e-mailed Don about it a few years ago, and by then he had become aware of the concept.

I guess this Don person never traveled outside North America.

We have the same thing in Japan; they look almost identical to the controls I've seen in Germany. I just leave the temperature control set to the same position, and turn the other side to get the flow rate I want. It's amazing that Americans don't even know these things exist, and are still using ancient pressure controls instead.