Actually, fuck it, I have now been officially sucked into thinking about taps. Here we go....
Firstly, I think that there was an assumption that as a proud Englishman, I would prefer the two tap system, but, let me make it clear, I am NOT arguing that having separate taps is better. I agree that in almost* every imaginable scenario the single version is better for the reasons admirably summarised and lucidly described by
@suspended above. In fact, I think that everyone does agree, or at least half agree, cos every house I ever lived in had the single tap thing in the kitchen and the double version in the toilet and bathroom sink, sometimes reverting to the single tap system once more in the bath.
So, I agree that it is perplexing when you are first hit by the apparent discovery that UK tap technology has not yet reached the level at which it can develop the single flow system which allows the continuum of temperatures one desires and expects; and then one is confronted by the almost worse discovery that the builders and plumbers are indeed aware that this can be done and are in fact capable of producing that very system (possessing both the knowledge and the materials), yet, seemingly are also incapable of following the simple - and I believe irrefutable - argument laid out by Gus (and other tap obsessives before him) clearly demonstrating the superiority of one system - with the result that they somehow hedge their bets and make approximately half of the taps in a given house one way, and the other half, the other.
I and I suspect most of the rest of you have seen the reaction of Americans (and people from other countries, in fact probably all countries) over the years to their first meeting with a double-tap sink. Normally there is hilarity, perhaps some photographs shared on their social media for others to laugh with them, but it quickly becomes apparent it is nervous laughter, covering fear, cos normally they continue as though confronted by some kind of diabolical hydraulical conundrum which must be solved before the weary traveller can gain access to the life giving, cleansing fluid....
And it's this that kinda surprises me.... yes, the system that some houses in the UK use on some of their sinks is mildly worse than the system that other countries opt for, there is a possible delay of a few seconds in some situations, perhaps occasionally even some other kind of incredibly miniscule inconvenience that I can't think of off the top of my head, but I'm surprised that there are people who care enough this to talk about it and take pictures of the tap; yes just by statistics and so on I get that there could be one or even two people out there boring enough to do so... but seemingly there are millions and millions of them, constantly being amazed, staggered, blown away by this insanity, feeling the need to document it yet again, to prove that all of their other faucet fucking predecessors were not lying, those other trillions of photos out there, diligently recorded by tap geeks were in fact real and not the product of some kind of gigantic international tap hoax. I suppose that what I am saying is, who cares?
*And I say "almost" here only for the sake (now that I am, after all, giving up a rather large number of seconds which, when you think about it, could have instead been spent smoking heroin while having my dick sucked) of completeness, which I suppose demands that I should point out that one can dream up a number of artificial scenarios in which you might need two streams at different temperatures or something....