When the collaboration of the citizens is not required to generate wealth, dictators emerge. For Venezuela, it's oil.
We are also seeing how technology is generating enough wealth and power to allow tech companies to compete against society. Today, it's tracking people for advertising purposes, tomorrow it could be a mass surveillance at the scale of what is emerging in China.
Also USA, Brazil, Mexico, the UK, Colombia, Ecuador... there are more, but it depends on what you mean by "oil-rich". Ecuador, for example, produces less oil than Norway, but its oil production is a higher percentage of their GDP.
I define "oil-rich" in such a way that oil revenue is the dominant part of the economy. This would exclude the US and UK, for instance. (In fact, not even Canada might qualify by this metric.)
Of course, this is almost tautological, since any liberal democracy worth its salt ends up with an economy that does a lot more than simple resource extraction.
I would have to research the other Western Hemisphere examples you mention, though with the levels of corruption and often outright civil war in many of them, I would question whether they qualify as "liberal democracies" (or perhaps I should add the qualifier, "stable").
No. It's really not. The technical puzzle pieces are all there and well understood. Anyone who can amass the political power could get it done. Done fast or done slowly might require differing amounts of power.
Ad tracking technology is in no way related to wide spread blocking of internet content. Those are completely separate. To filter the internet you don't need to know the browsing or shopping habits of a single individual.
When the collaboration of the citizens is not required to generate wealth, dictators emerge. For Venezuela, it's oil.
We are also seeing how technology is generating enough wealth and power to allow tech companies to compete against society. Today, it's tracking people for advertising purposes, tomorrow it could be a mass surveillance at the scale of what is emerging in China.