A lot of people coercing and vilifying don't care that they might possibly be wrong, and a lot of retrospective vote analysis can be made based on demographics or things other than overt stances. Alice might stand out in sufficiently small groups simply by not being an overt liberal, whilst Bob might stand out in a much larger group not for his quiet avoidance of discussion about politics but because it's pretty damn unlikely that the white church attendees in the village voted for the Nation of Islam

It's pretty obvious that the degree of comfort someone in Bob's situation has in voting for something associated with his highly visible minority status is closely linked to the size of the electorate relative to the size of his minority. The secret of his radicalism would be entirely safe if votes were tabulated at state level, and certainly exposed if it's tablulated at polling station level and he's the only black guy there. And the world has no shortage are stark divides and identifiable groups who are tolerated a lot more when they're not perceived as politically active or at least not in that way. Some of the political causes that can be problematic for some voters when ballots aren't secret enough aren't even that ugly or that fringe...

The same goes for fairly quite and much less visible Alices. The three people who voted against continued British sovereignty over the Falklands Islands [turnout: 1518] successfully kept their secret from a population which had its fair share of outrage. Wouldn't have been very likely they would have succeeded, or necessarily felt safe to vote in the first place, in the hypothetical event it would be reported that all three came from the Port Howard [Population: 20] polling station.