And one reason why this is so is fraternizing - a crime in the military and frowned upon at the factory. If you are a salary-man, you are expected to avoid being friendly with the hourly employees. You aren't supposed to go out to the bar for a beer with them after work, and even if you did, you'd make them feel uncomfortable more than you'd be. The lower classes want to hang with their own.
Even in Communist countries, where everyone is "equal" there are some more equal than others, with party members and the politburo on the top of the heap, managers and engineers somewhere in the middle, and the workers and farmers at the bottom.
Why is it we have this need to have someone above us? It is a survival instinct, of course. Humans are like ants in one regard - we work together cooperatively to do amazing things, which is one reason why these "sovereign nation" people are full of horseshit. Every single thing in your life from your house, to your car, to your computer, to your coffee cup and the coffee in it, required an intricate ballet of hundreds of thousands - if not millions - of people to produce and ship to you. Without an organized society, none of this would happen.