The spread of rhoticity and Non-rhoticity

I find it interesting that rhoticity is rapidly spreading in the United States at the same time that non-rhoticity is rapidly spreading in the United Kingdom.
Why are your thoughts on this?

Did you take a poll?

I find it interesting that people keep on making comments on things they don't understand (and in a language they don't know).

"rhoticity is rapidly spreading in the United States"

Your stupidity is spreading on this forum.

I don't think the two phenomena are related to each other directly; i.e. that one country is huffily saying "If that's the way THEY'RE going to talk, we'll just have to do the opposite!" I think it just reflects that the dominant form in the US is rhotic and that is setting the norm there, while the dominant form in the UK is non-rhotic and is doing the same there.