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"A pint of Stella, please" is a perfectly polite way of asking for that product. Similarly, "A day return to Southampton, please" or "Two granary rolls and a pasty, please" or endless millions of other such requests.
My point is that this, "Can I get..." approach is relatively recent and seems to be used only by people under 30.
Accordingly, I imagined someone might point out that it is how some popular soap characters make such questions. For example, the questioning tone used by the same British age-group at the end of sentences when the words are a statement, not a question, was often blamed on the impact of Australian speech-patterns in 'Neighbours' and 'Home and Away'.
So, does anyone actually have an answer for me?