Naturally, people from the same country should speak more like each other; and people from different countries would have more different accents. English has grown so diverse that there are different words and expressions for things in different areas. Plus, the accents make them sound so different from each other. You might even need an interpreter when you're talking to somebody from a different English-speaking country (not to mention when people are speaking English as a foreign language)!
But sometimes, even people from the same country have quite different accents; for example, the United States. People from Alabama speak differently than people in New York, and they both speak differently than people from Wisconsin. And some of them have accents so strong you can barely understand them! Of course, it doesn't seem that way to them. But how does that happen - why are there even different accents? Alabama isn't all that far away from New York - why are people from New York and Alabama speaking differently from each other? New York City and Boston aren't that far away - but those people sound different from each other. Even people from New York City and upstate New York sound different - and that's the same state!
Then, there's the so-called "neutral" English accent. Is the "neutral" accent in one country the same as in another country? And, what does that mean? In the U.S., we seem to think that this is a "mid-Western" accent. Sometimes it's called a "TV accent." Most national TV news anchors and reporters don't seem to have a regional accent - they seem to have the "neutral" accent, right? Even people who star in shows that take place in spots where there are strong accents don't necessarily have that accent. And, how does one particular accent get to be the "neutral" one? I guess because we all understand them, and we can't tell where they're from.
Some people think that television is actually going to kill-off regional accents. These neutral people are beemed (or cabled) into our homes. Everyone listens to the same neutral voices, and adjusts to them. Soon, everyone will talk the same. This is a good thing: We'll all be able to communicate easily, right? Or, is it worthwhile to have accents?