There's actually a phonetic term for "leaning heavily on the R":

https://en.wikipedia.org/wiki/Rhoticity_in_English

>Rhoticity in English is the pronunciation of the historical rhotic consonant /r/ in all contexts by speakers of certain varieties of English. The presence or absence of rhoticity is one of the most prominent distinctions by which varieties of English can be classified. In rhotic varieties, the historical English /r/ sound is preserved in all pronunciation contexts. In non-rhotic varieties, speakers no longer pronounce /r/ in postvocalic environments—that is, when it is immediately after a vowel and not followed by another vowel. For example, in isolation, a rhotic English speaker pronounces the words hard and butter as /ˈhɑːrd/ and /ˈbʌtər/, whereas a non-rhotic speaker "drops" or "deletes" the /r/ sound, pronouncing them as /ˈhɑːd/ and /ˈbʌtə/. When an r is at the end of a word but the next word begins with a vowel, as in the phrase "better apples", most non-rhotic speakers will pronounce the /r/ in that position (the linking R), since it is followed by a vowel in this case. (Not all non-rhotic varieties use the linking R; for example, it is absent in non-rhotic varieties of Southern American English.)

>The rhotic varieties of English include the dialects of South West England, Scotland, Ireland, and most of the United States and Canada. The non-rhotic varieties include most of the dialects of modern England, Wales, Australia, New Zealand, and South Africa. In some varieties, such as those of some parts of the southern and northeastern United States, rhoticity is a sociolinguistic variable: postvocalic r is deleted depending on an array of social factors such as the speaker's age, social class, ethnicity, or the degree of formality of the speech event.

In my original comment:

> (rhotic vs non-rhotic).

:-)

The single most significant factor for the popularity of American accents is Hollywood.

My brothers and I did the ring road in Iceland a few years ago. One night we were eating dinner at a restaurant in a small village in North Iceland. Our server had a perfect North USA dialect of English. He sounded to us just like an American. We asked him if he had lived in the USA. He said he had never left his village and had never even been to Reykjavík. We asked him how he came to speak American English so perfectly and he said he learned it from watching movies and TV shows.

I'd include the US music industry in that. Songs are <<super>> important for learning a language, if you're constantly surrounded by songs of a certain language.

Plus... American multinationals are somewhat close behind. If you want to get a good, well paying job at an American multinational, you have to speak English at least a bit, and you have to know it well if you want to move up the ladder.

Recently we were doing interviews for a job. We had one gentleman from India applying for the position. We have hundreds of people with Indian English accents at our company, so it’s not like we are unfamiliar with the dialect. But this person… none of us could understand more than one word in ten from him. We persevered with the interview, each of us assuming that it was just us and everyone else could understand him. It took me nearly an hour to realize that he was pronouncing API as “ape-ee”.

For regular songs (not rapping) it's a lot harder to distinguish Brits vs Americans, I've found, as compared to speaking.

People pronounce differently when singing vs speaking.

I like British accent for its aesthetics, but from pragmatic point of view it's not even a contest (from the perspective of a non-native speaker), I agree.

It's not just the r's (in fact, some British accents are rhotic - around their South West, if I'm not mistaken?), there are all these glottal stops and whatnot.

But, from my observations at least, there are also big discrepancies related to social class. When I moved to the UK, I had no problem whatsoever talking to, say, a local librarian - but a plumber would be nearly impossible to understand for me, in the first months at least. I didn't really experience it in the US, certainly not to such an extent.

The thing is that UK dialects are virtually unknown outside the country; they can be very different from Received Pronounciation, but diverge in ways that are still fundamentally predictable for a native English speaker (unless you wander into Scotland or Ireland).

American accents are more familiar because of Hollywood, so they tend to be less surprising; and likely because a lot of them were actually developed by people who learned English as a second language, they are often exaggerate in effect, very clear, and actually more regular (particularly on names, where UK "rules" are anything but).

This said, "deep south" US accents, when pushed hard, can become as inscrutable as certain UK dialects.

What does that even mean? There's nothing clearer or more explicit about either. Maybe you mean that it closer matches the orthography?

> than act like the letter doesn't exist (rhotic vs non-rhotic).

Every language changes. Nobody is acting like "the letter doesn't exist", just occasionally that phoneme has changed or dropped in their dialect. Even in non-rhotic accents, an r in the orthography can indicate a change in vowel quality.

> I think it's another factor why American English is more popular than British English (besides the huge economic factor, the US economy being 5x the UK one),

I think the greater population, and the fact that the Hollywood content has embedded itself globally, has resulted in more exposure to American content (of which there is more of). Any dialect will sound clearer to you if you're exposed to it more often than others.

That's funny. As a non-native (German) English speaker, British pronounciation seems far clearer to me than American - barring strong regional accents of course, maybe thatis what you had in mind.