Meanwhile, every European shower I've ever used is so tiny that I knock my elbows on the walls when I reach up to wash my hair. In short, the world is a place of contrasts.

*Some American showers. Probably most, but plenty of them allow for controlling both. My shower has a separate temperature control that can be left at the desired setting.

Hold on, am I missing out on some shower innovations?

I’ve never heard of this pressure control

What we get here in the rest of the world, is something that allows for control of both temperature & water flow. Usually (but I can't really speak generally) with a freely-moving showerhead connected by a metal-jacketed rubber hose (which can be placed on a fixed position to the wall for overhead showering)

We have those too. In particular, I have one of those. You can buy them at Wal-Mart. I rent and I take it with me when I move (re-installing the original hardware).

Here's what it looks like:

left-right controls the temperature, up-down controls the flux

The smaller knob controls if the water goes to the showerhead or just out the faucet

https://www.kludirak.com/pub/media/catalog/product/cache/b3b...

These are showers with two controls; one for temperature, another for flow. There are two main types (IANAPlumber):

Pressure-balanced valve - https://en.wikipedia.org/wiki/Pressure-balanced_valve

> A pressure-balanced valve provides water at nearly constant temperature to a shower or bathtub, despite pressure fluctuations in either the hot or cold supply lines.

thermostatic showers - https://www.steamshowerparts.co.uk/how-to/thermostatic-showe...

> A thermostatic shower seems like a regular shower, but it has something very unique inside; a thermostatic valve. Thermostatic valves mix both hot and cold water together to a consistent predetermined temperature, preventing scalding and thermic shock.

FWIW, a pressure balancer is usually only required if the supply to the shower is too small.

This type of control is more common for a kitchen sink faucet in the U.S. than the bathroom.

Just picture a one-handle kitchen faucet with a long hose attached. At the end of the hose is the shower head.

It’s much easier to convert an old tub faucet to a shower this way, than by opening up the wall to run a pipe up to a fixed shower head.

Here in Brazil, we usually have either two separate controls, one for cold water flow and one for hot water flow, or when using an electric shower head, a single control for water flow (and a winter/summer/off control for the temperature in the shower head).