There's a couple aspects: one is that there are fewer Wall Street people and Capitalists than there are workers, and when you take in to account how frequently anyone would run into these people due to class structures in society it becomes even smaller, so statistically any interaction is more likely going to be between workers.

Another is that Americans have a Pavlovian love for their Police and Feds, it's all over the tv and movies, it's in the schools, it's in the news. So the chances of someone pulling a Dorner are pretty slim too.

Finally, Americans are so incapable of viewing society in any form of class structure, IE understanding who has power over them, that the only people they are capable of viewing with power are ones they've had interpersonal relationships with: Teachers who scolded them, a waitress that told them they had Pepsi rather than Coke, the bartender who cut them off, etc.