I'm not convinced they target any better than the newspapers. I'm British and FB's targeting showed me an ad for how to renounce "Your US Citizenship for tax purposes", local news for a city I've never been to in Florida, and my response to the Brexit referendum result was to move to Berlin yet FB is showing me UK-specific ads. YouTube is no better, showing me an ad fronted by Nigel Farage, and a lot of obvious scams that couldn't (at the time) be reported. Twitter, back when it was that, classified me as being interested in three languages I can't speak and spectator sports I've never once watched.

It is of course possible that I'm merely weird enough that the optimisers can't figure me out. Anecdotes don't make for good datasets.