Gentrification isn’t just taking place in working-class neighborhoods. It’s happening to jobs, too.

Walk around parts of Brooklyn, Portland or Pittsburgh, and you’ll find stylish cocktail bars, barbers and the occasional butcher shop staffed by young, college-educated employees. For an affluent segment of today’s urban economy, these jobs have been revalued from low-status semi-manual labor to glamorous occupations, says sociologist Richard Ocejo.

In...