Oh, it was obvious, but you're analogy was not. Coal miners typically make almost $22.00 per hour, which is middle class wages.
Lower class are those who make minimum wage, or just barely over it. (Adults who are workers at McDonalds, or baggers at the grocery store, etc.) But no one thinks they don't work hard. The ones who don't work hard are the people who are capable of working yet have been on welfare for years. Those are the ones we complain about.