You can always arbitrarily divide people into two groups by making one "everybody else", but the two groups you name are not coherent classes. (Not even the first, which overlaps both [a relatively well paid segment of] the working class and the petite bourgeoisie, but especially not the second, which spans from the lowest of the working class to the highest end of the rentier/capitalist class.)
Sure, they are. "tech workers" tend to work in tech companies. "everyone else" tend not to work in tech companies. It's quite coherent. Are there exceptions? Of course. Does the presence of exceptions mean the classes are incoherent? Of course not.