Like, specifically that term, or just the idea that there are a lot of poor people and very few rich people? If the latter, definitely a lot of Springsteen would fit. Ghost of Tom Joad (most of the album), My Hometown, Death to My Hometown, Jack of All Trades, Seeds, This Hard Land... probably a lot more, really. Maybe Billy Joel, Allentown. Dropkick Murphys - quite a bit of their stuff, but maybe especially Workers Song. Billy Bragg, Power in a Union?
In the last thirty years the gap between high income and middle income families has doubled. How come we never post any debates about this, yet have hundreds in regards to other social inequalities?
You're asking why someone else doesn't start the conversation you want to see started? Start a thread. Income inequality began to rise when Reagan rejected The New Deal philosophy and started the false talking point that all poor people were leeches on the system. I'm happy to join in such a discussion but don't care to start one.
It would could be a really interesting discussion, but I can see from @GingerCoffee's reply it would just end up in the (boring partisan political) Debate Room.
Something like a black teenager getting shot hits the news. Something like increasing inequality in wages is a matter of statistics, which may get headlines (on a quiet day if the editor has been told that the paper wants to push it) when a report has just been published. It's something that's been quietly happening for years, not something that happened yesterday.