What happened to the lower class and the upper class, do they no longer exist?
We want to believe that most people are middle class so we imagine that a graph of class division looks like a well-balanced bell curve with only a few in the lower and upper classes. The vast majority of us are somewhere in the middle.
Nothing could be further from the truth!
A more honest graph of class division is a skewed curve with the majority of the people in the lower class. The middle class is not statistically in the middle and it does not conform to any of the central measures such as the mean (average), median (middle) or mode (most frequent).
The middle class is more correctly an intermediate class that is between the lower and upper classes.
Everybody wants to be in the middle and nobody wants to be part of the outgroup, so we have relabeled the lower and upper classes as the lower middle class and upper middle class respectively. The outgroup now only consists of the very poor and the very wealthy and they are no longer regarded as classes.
This social agreement to reduce those who are in the outgroup to only those who are very poor and very wealthy makes any conversation about class division almost impossible. The lower class people do not want to be lumped in with the very poor who they regard as their inferiors. The upper class people fancy themselves to be hard-working people and do not want to imagine that their high income lifestyle is largely at the expense of low income people.
Nobody wants to be in the lower or upper class so nobody has to admit they are or even admit that these classes of people exist.
Whether we admit it or not, class division is a thing and until we admit it we can't talk about it.