What I find more interesting about this is that's it's due to cultural evolution. I'm British and if you walk around a churchyard you'll see the older gravestones all use what is now the US format. That was the original format we used but at some point, someone decided it was more logical to use ascending order and eventually that became universally used. The USA is still yet to make that step. It's the same with most of the US English language differences in spelling and pronunciation. The US still uses a lot of old English and the 2 languages evolve separately.
They can be used together by people around the world. In my experience, I see US-English is shorter than UK-English. The USA tend to shorten words and I think it is helpful practically.
For common words I think people can understand both styles and in common conversation, we don't need too many words to make it fluently. We don't need to many old or complicated words to communicate with each other.