My shower insight…until recently (when my building got solar) I had very high electric bills…to combat that, i stopped turning on the water heater…it took a while to adjust to…but now, my showers are faster (less water waste) and its better for you…and in my experience this is not a myth. I live in a constant warm climate and I am older…my skin is visibly healthier and my hair is softer…no expensive products…just cold water!

now, although my Luma bills are minimal(due to solar panels), I still do the cold showers, just for the “no-cost” skin care.

but more directly…people (who have it) love those water controls! I remember years ago “hooking up” with a guy in a fancy apartment. He invited me to use shower after, but implored me, “Whatever you do, don’t change my water temp setting!” I didn’t touch it, but it was my first time seeing anything like this…i remember thinking, “rich people don’t even have to adjust their water…they can even control and preset that!”

Problem is, you need a simple/robust mechanism to physically mix the two streams of water.

The concept of a digital shower thermostat does exist, where you set a temperature in °C and then a thermometer in the mixed stream triggers an electric motor to move the mixing valve.
But as far as I can tell, no companies with a reputation to lose do offer that, because you have far more parts that can fail.

You could do a transmission, where you turn the handle across 120° and the mixing valve only moves by e.g. 30°.
That would make it easier to hit your preferred temperature, but you would lose the ability to make it fully hot or fully cold and the manufacturer doesn’t know how hot/cold your water streams are, so there would need to be a way of adjusting which 30° angle you get.

I guess, instead of a handle, one could have a turning knob with a transmission, so you’d need e.g. three revolutions to go from cold to hot. Then it wouldn’t be possible to tell visually to what it’s set right now, though.

So yeah, hopefully unsurprisingly, manufacturers aren’t just being dumb. There are physical limitations that make this non-trivial.

We recently remodeled the shower and the facuet we got apparently only let’s you use warm water if you have it on full blast which sucks because I love showering with just a tiny bit of warm water so the soap doesn’t all get washed away and go down the drain.

Want to replace it with a more sane faucet but I’ll have to pull some of the tile off the wall, which I actually need to do anyway to fix the water spout the tile guy installed incorrectly.

There are plenty of thermostat regulated shower taps. They’ve been around for decades and do exactly what the author wants.