Korvo, when I was growing up in the 1950's, I think the three classes were much as you describe.
Now, idk...it's different...as I look online, sometimes there is a differentiation made between the middle class and the working class; the current working class being what you describe as the lower class.
Then, the lower classes are much as Other Tink describes, except that I would describe the lower classes with sympathy for them, especially since I am part of them!
Also, I think here in the US there might now be another class, the super-rich elite; and they are maybe only 1/2 of one percent of the population, but they control the government and the politics and the economy too, along with the system of jurisprudence. Apparently, this tiny group has been able to arrange things so that they pay very little in taxes, and so that ever more of our national wealth moves into their control, and the rest of us are unaware or something, but somehow we have not been able to use the vote to correct this unwholesome situation.
So the class arrangement is changing and I don't really understand it but I am worried!