Much, much worse is the US mm/DD/yyyy format, especially if mixed with DD/mm/yyyy format, unlabeled, in the same file.
So do Europeans analogously refuse to use anything except decimal points, except where they have to?
Displaying English-formatted numbers is incorrect in the rest of Europe, and will confuse users. Programming languages handle this, but you still write pi = 3.14 in the code.
Note 123.456,78 is German, but Swiss is 123'456,78. I think.
(Displaying miles and yards, inches and 'letter' sized paper is also incorrect, but it's unfortunately not uncommon.)