Required? In the states? Nah. My last house in the states was built in 2000, not a single balancing valve or thermostatic valve in the place. 4 bed 2.5 bath.

Not just the states….im in a (rented) house in Germany that was built in the 90s (so not that old to compare to a lot of other houses here) and deal with this everyday. Coupled with the insanely long cleaning times and frequency of use due to how small they are for the “economic” washing machines and dishwashers, fluctuating water pressure and water temps are always a surprise….

That’s how it is in a lot of places in Europe, i think anywhere outside of the bigger cities. The bus routes where i live in Germany are all once an hour. Gets less often at night on weekends, but we still pay for them.