I had a very shower-y shower thought: why does turning my shower handle a tiny bit make such a huge difference in the comfort of the shower? Why are we wasting so much potential control area on water temperatures that no one wants? Who cares about ice...
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.