I work with Americans and this hits home hard. It's especially infuriating when they format their dates. "I had a meeting with so-and-so on 4/5" and nobody has any fucking clue what they mean.
The worst part is how hopelessly oblivious they are about it. It's not even like they don't care that nobody does things their stupid way - it's the fact that they're so insulated that they can't even fathom that nobody does things the same way they do. It just goes to show how clueless they are about the rest of the world and how little they get out of their neighborhoods.
It drives me mad. At this point, it's just offensive how ignorant they can be sometimes. If you have to work with other people, you should at least make an effort to be aware of the fact that others do things a different way and try to avoid situations like this, but they just refuse to do so.
