I just visited some web galleries of bathroom remodelers in the US, and it looks uncommon to have external shower fixtures. They tend to bury as much of the fixture as possible in the wall. From the photos, I don’t get the impression they are using thermostatic mixing valves. But it’s hard to tell. Can anyone confirm or deny?
I think I might favor external fixtures because they tend to be much cheaper and also more easily servicable.
Yeah, high end installations have been using them for years. You won’t find them in the big-box stores. I looked into all that when I redid my showers and decided to just go with Delta “Monitor” mixers. It worked pretty well with the old tank heater and it’s indistinguishable from a thermostatic now that I have an on-demand water heater. As a bonus, the Monitor valve is interchangeable with a regular mixer valve in case I’m broke when it fails and need to buy a cheap mixer valve.
I think the Monitor brand uses wax like you described in a comment but they don’t call them thermostatic, probably to differentiate them from their actual bimetal products.