Thermal regulating shower/bath faucets are relatively common: https://www.deltafaucet.com/design-innovation/innovations/sh...

I have one in my master shower and it's fantastic. Of course, the water starts out cold (because the water in the hot water pipes are cold) but once it's up to temperature, it's very consistent, even if you have a toilet flush in your house which would reduce the pressure of cold.

> Of course, the water starts out cold (because the water in the hot water pipes are cold)

No, this should be considered a failure condition for a constant temperature shower. I don't care how they do it, just bleed the cold water into a separate pipe off to the side or something.

We have sent people into space, I want actual uniform temperature water.

ah, you want this, which also exists: https://www.finehomebuilding.com/2013/03/07/hot-water-circul...

the way I do it is just turn the shower on about 30 seconds before I get in, which works the same with half the piping and less energy loss due to circulating hot water (but some water loss)

I've seen a few apartments in Asia have small electric water heaters right before the faucet. They provide instant hot water until the main boiler's hot water arrives.

This is fairly common in newish kitchens in the Netherlands too, especially if the kitchen is far away from the boiler. Sometimes even with a boiling water tap, so you don't even need a kettle anymore.

A toilet flush should either:

- not drop the pressure of the cold water at all

- drop both the hot and the cold equally (due to house input being limited)

The hot water is fed by the same input pressure as the cold, so they are the same pressure system. A temperature drop on a toilet flush is a pretty big fuckup by the plumber in the bathroom.

Everything about fancy hotel bathrooms is a usability nightmare. Sometimes there are two showers (hand-held and ceiling-mounted) operated by a single lever which sets temperature, pressure, and which of the two showers is active. The risk of giving yourself a too hot or too cold burst is significant. I usually cower into a corner while sloooooowly messing with that lever.

For an extra bonus: You usually have three identical looking small bottles with 'shampoo', 'conditioner', and 'shower gel' only distinguished by a tiny label, something like black-on-brown or yellow-on-white. Good luck if you are wearing glasses.

Stayed at a hotel with a faucet with some of the features you described - button-push and straightforward temperature control - and it was one of the best shower experiences I’ve ever had. Would be putting one of these in my own master bathroom if it wasn’t so expensive.

https://www.hansgrohe-usa.com/articledetail-showerselect-the...

Thermostatic mixer showers are very common (in the UK at least) and are very affordable (sub $100) and as reliable as your hot water supply. My understanding is that water pressure is much harder to control for; there's so many variables that you just can't do anything about, and without installing a giant tank and a pump if your pressure is low it's always going to be low.