The problem with fields like IT is that the people who can make unions effective are also already employed and likely making decent money, so they have little or not enough incentive to unionize. The worst thing that can usually happen to them is layoffs, and in that case there might be a lot of copium in the form of "It won't happen to me".

Yeah, big numbers and big crowds are useless, if there is no unity, no tendency to help fellow worker. As you point out "it won't happen to me" attitude is precisely why a handful of dudes who run big tech can get away with almost anything. "It won't happen to me" works, until it doesn't. By then it will be too late (maybe it is already too late?) to bring out any meaningful change