Accent-leveling

Today, someone from Kyushu and someone from Hokkaido can speak to each other with relative ease, as they've both likely mastered the Standard Japanese dialect as well as their own local one. Likewise, a factory worker from Scotland and one from South Africa have probably seen at least some of the same TV shows and movies - and hence are probably capable of communicating in some approximation of a shared English. Modern media has done a lot to facilitate communication between people who, though they may nominally speak the same language, grew up with very different "versions" of it.

One difference between the former and latter examples above though is that there is a "standard" dialect of Japanese in which business and government communication is made, everywhere in Japan. People may say なにしよっと or なにしとん to their families and friends, but when they meet each other they know to use なにしている. There are several standard dialects of English, at least one per country in which it is spoken. Therefore a Welsh woman and a New Yorker grew up not just speaking differently to their peers, but recognizing a different set of standards for formal communication as well. There's no one "Standard English" that applies to English speakers worldwide.

However, teenagers in England listen to American hip-hop, and an Australian wildlife TV show can be a huge hit in the US. We may recognize different standards of this language we call English, but thanks to the global media, we're at least familiar enough with each others' differences that we can still communicate successfully.