I've been wondering what this is for a while, and finally got round to looking it up. The word 'pretentious' comes to mind: https://en.wikipedia.org/wiki/Flat_white

I'll stick with my instant decaff thanks.

Pretentious being the right word.I always aggravate and ask for straight forward normal coffee and often they pretend not to understand.
''Flat white' seems to be another instance to charge more.

And what about the 'delicacies' such as fried potato skins and pea pods which we used to give to the rabbits or pigs.
I'm sure there are plenty more examples.

I'm not a big drinker of coffee, but if I go out for a coffee , it will be Marks & Spencers. I enjoy that, very nice staff too. I usually get a pot of tea as you get two cups as opposed to only one if you get coffee.
I do not like all the new fandangled drinks in the big chain expensive coffee shops I never, go in them.