Social classes existed before; when revolutions occurred, the composition of each class and the composition of society into classes change. Just like there are

Social classes existed before; when revolutions occurred, the composition of each class and the composition of society into classes change. Just like there are almost 50% of women in a society, the bottom social class (in terms of power, money, etc) is huge. So, whatever mobility one perceives is in the bottom class: moving from $15 hour security guard job to $150K jr dev job. People from non-American countries recognize this. However, in America, the bottom class since WWII till late 1970's, had a nice job, pension, a home, two cars, with one spouse working; this created the illusion of 'class less' society in America. When one says that there is no mobility, we are comparing the life of today with that of post-WW2 middle class era. Even if we look at John Rawls, his difference principle does not eradicate classes. Basically, that principle in one version is same as "a rising tide lifting all boats"; in another version, it is fair to lift some poor boats higher than other boats, even at the expense of the latter.