Notting Hill Station announce and tube comming.wav

You hear basically the same announcement about unattended bags being destroyed at JFK Airport in New York, so I don't think it's a British thing specifically.

The only subway system in the U.S. that I know of that has a significant problem with gaps (which, of course, are created at stations with curved platforms) is the New York system, which uses "gap filler" devices instead of warning people.

I've heard the reminder not to leave belongings unattended around the San Francisco Bay Area, but never heard "mind the gap" or a similar warning on BART or MUNI. Some of the announcements I haven't heard in the Bay Area. Maybe Americans are more careful than the British. Destroying unattended belongings sounds extreme.