So are you arguing that CSS should also be localized? (In my opinion that would clearly be a terrible idea, and most of the reasons why apply to Gmail as well)
I mean, it would be lovely if HTML (invented by a British English speaker) used en_GB throughout. I think it's only "dialogue" which is misspelled in HTML5. Although the obsolete "centre" element is also wrong ;-)
Well I much prefer as an Australian to develop programs, not programmes. My analog to digital converters work just as well without vaguely French "ue" extensions.
Single items of information are still data, not datum.
Among many things in HTTP/HTML/etc that bug me is "referer".