there is an argument that humans develop immunity to sales techniques, and social media advertising is too new, and we have yet to produce mind-antibodies.

I mean, it's also possible that targeted advertising is just that much better than previous methods of advertising... I'm just bringing up the possibility.

It would be interesting to look at other major advances in advertising technology and see what excesses they produced. I mean, it's not quite the same, but it is said that in the Kennedy/Nixon debates, people who listened on the radio thought Nixon won, while those watching TV thought Kennedy won. I mean, it was another inflection point in advertising where new advertising technologies possibly gave us a different president.

Maybe countries should be split by political views rather the geography.

In some ways we do. My understanding is that the political meaning of 'white people living south of the mason-dixon line' has remained far more stable (even before there was a masion-dixon line) than the definition of 'democrat' or 'republican'

But in America, it goes beyond where you live being predictive of how you vote; in America, in a real way, we give land votes; a person in a less populous state has dramatically more effect on the outcome of an election than a person in a more populous state.

(and then, of course, the obvious; we do have dramatically different laws in different states. )