Cultural challenges

Train Station, Coffee shop (I won't mention the name), 8am of a typical commuting day

Barista: Yes, please!
Me: Can I have a single espresso, please?
Barista: Sure!
(Barista goes to the coffee machine, but suddently comes back)
Barista: Sir, sure you want a single espresso? The Double espresso has the same price.
Me: Yes, I am sure, thanks.
Barista: (Baffled) Uh... Ok!

(Although, the most upsetting thing, after this conversation, is when the cup is 3/4 full)