I think there's always been a good mix of topics. 9 to 5 is probably a classic in the genre of barely making it. I tend towards folk and country though, so I think of lack-of-money as being a standard song topic. Rhinestone Cowboy fits well, too, but it's more "poor dreaming of being rich."

Bad, Bad Leroy Brown drove an Eldorado so I'm guessing Cadillacs had some cache back then.