2:35 PM
Your last three sentences alone give it more thought than anything any Russian would give it over the course of their entire life.
I can tell if you're from Dagestan, Georgia or Lithuania. And I can tell from your vocabulary, though not accent, if you're from Ukraine or St. Petersburg. But I don't think I could possibly tell someone from Vladivostok from someone from Ekaterinburg.
And those are what, 5000 miles apart?
Your education does not matter. That, again, would manifest itself in vocabulary over pronunciation.
We should consider that all Slavic languages even today are still mutually intelligible to a frankly obscene degree. It's a well documented curiousity, as well as the fact that Holland and England are on the exact opposite end of the spectrum, with even neighboring dialects sometimes being mutually unintelligible.
I have a co-worker from Sofia who speaks Bulgarian with her daughter. I understand everything they say even though I couldn't produce it myself. (And so conversely, I just speak Russian with them. And they don't bat an eye. And the girl is like four years old, she probably doesn't even know that Russian exists. But she's able to understand me.)
Now try being a Swabian and travelling just 50 miles east to Lotharingia, or 50 miles west to Bavaria. For all the mutual intelligibility you will experience, you might as well be coming from Mars.
And those are mere dialects of the same language. Whereas Russian, Bulgarian, and Polish are not just separate languages, but indeed languages from three different language families. Measuring thousands of miles across in every which direction.
So given how comparably tiny the difference is on such large a scale, it only makes sense that the differences within each language would be minuscule.
@Færd so no I wouldn't blame it on the USSR per se. This development, or rather lack thereof, goes back a full 1500 years.