"I believe that this is part of the heritage of racism and slavery in the US. White Americans, naturally and unconsciously, assume that "someone else" will always be there to do the hardest work for the least compensation, essentially subsidizing a degree of comfort and relative affluence for the majority, and allowing even the least privileged members of that majority to think of themselves as part of a well-off upper-middle-class society."

I don't think this makes a great deal of sense. Only a small minority of Americans ever benefited from slavery (mainly New England merchants and large Southern landholders). Most of the time, most Americans have had to do their share of the 'dirty work'.