Most working-class plotlines are also middle-class plotlines; the difference would be in the attitudes toward them and actions taken about them. (Although investments and "buying new houses" are both topics of very limited appeal to the working-class people I know; they're rather like "run for president"--sure, someone'll do it, but it's not going to be me.)
However, neither class's category of plotlines includes "create serum that allows humans to breed with plants."
Shows focused around strong sci-fi elements are outside of the class structure system. Even if they draw from those systems, even if they accidentally or deliberately show the creators' biases and preferences... they're not showing "working class life" or "middle class life;" they're depicting "human interaction with [aliens/bizarre tech/superpowers/sentient seashells/whatever]."
And I'm not claiming comedies, or dramatic comedies, or comedy-dramas, can't have good, realistic depictions of working-class characters. I'm not looking for comedies. (Also, not looking for British TV shows, which have a different basis for class structure. But noting which ones get recommended; I'll try looking into some of those.)
I'm looking for non-comedy shows, about working-class or lower-class characters living working-class or lower-class lives. Non-comedy is crucial (for reasons I know I mostly glossed over); "living working-class lives" is more negotiable.