Actually I think they're different. It's just that they're form the same region. Ireland isn't a part of the UK, unlike Scotland.
I think someone from New Orleans, Louisiana sounds very different than someone from Seattle, Washington but they're both from the United States. On the other hand, I think people from Vancouver, British Columbia don't really sound that much different than people from Seattle, Washington besides a couple of vowel inflections but they're from different countries. All three are still from North America.
If an English person was talking to a Scottish person while in the UK they might refer to all of the above as Yankees while none of them would really identify with it. The one from Vancouver isn't even from the States.
The revolutionary and civil wars were both fought prior to even the founding of the Western territories let alone Washington's statehood in 1889. The one from Seattle would identify as a Mariner or a Seahawk before they would identify themselves as a Yankee

.
The person from New Orleans might actually be offended depending.
I imagine it's more appropriate to stay as specific as possible depending on the company you're with or which hemisphere of the planet you're in, but I think on the whole, in this international community, people tend to be a bit more lenient.
All in all I liked all of the accents.