[Akath19]

It's mostly a US (not American, America is a continent after all) thing.

In Latin America getting laid off means being called to HR in the morning around 10:00am and getting told "you're being let go, please clean out your desk, fill in your boss on any pending work and finish your workday"

I've only seen one person escorted out of the building in the US way and that was because he was stealing corporate info.

[muninn_]

American refers to people form the United States in colloquial language across the globe, so the person you replied to was correct in their use of American.