Yeah, but I guess it's not only about vowels. As I understand, everything matters, speech patterns included. But yes, it never ceases to amaze me how some (many?? I really don't know) native English speakers determine other native speakers' background from their accent. What a scary superpower. Personally, I would be really surprised if anybody could say what region I'm from based on my "accent" in Russian only. Of course, people speak a little different in the republics, especially where Russian is de facto a second language, but Moscow, Novosibirsk, Vladivostok, Saint Petersburg? Almost no way to tell. Maybe there's a lonely Russian Henry Higgins somewhere that can do it without too much effort but it's usually not that easy for us ordinary people, don't you agree?
Manner of speaking, dialect and slang have always been the reflection of a step on so-called 'society ladder' in different countries all around the world
Kseniia is correct. It's fairly easy for most of us here in the states to determine an area of origin of the country based on accent and dialect.
Mrs Tad makes a good point. For example, Americans rarely ascend to corporate or even social heights with a southern accent. Of course, I'm referring to success outside of a local area where all of the speakers sound the same. Other accents won't pass the test either. But southern US is the classic example.