But you can easily remember the approximate position of the lever, which is all you really need to get appropriately warm water for hand washing. The problem with normal hot and cold taps is really that it’s hard to replicate the settings, even approximately. (Also, while you can try to remember “half turn cold, two turns hot”, you then have to do arithmetic to get any different flow - ew)

Since the cold water supply will fluctuate in temperature from day to day, you won’t actually get exactly the same temp unless you use a thermostatic mixer (which exist for showers but I’m guessing are hard to find if they exist for sinks, because… why would you need one?) even with your solution - so I think the single lever version is always good enough.

I don’t understand what centre-bias means here.