From Tim Harford:

That’s the conclusion of American economist Caitlin Knowles Myers. She, with her students as research assistants, staked out eight coffee shops (PDF) in the Boston area and watched how long it took men and women to be served. Her conclusion: Men get their coffee 20 seconds earlier than do women.

He wonders why competition has not eradicated this discrimination:

But racist or sexist businesses with many competitors are likely to be shut down by the bankruptcy courts long before the human rights lawyers get to them.

Other than the good reasons he mentions, I’d say that the reason is that 20 seconds isn’t really a noticeable amount of time.  If every coffee establishment I’ve ever been to had discriminated against me by delaying my order 20 seconds while they muttered bigoted obscenities under their breath, I don’t think I’d ever have noticed.

Via Radley Balko.