How long has it been since Mr. Gates has done his own shopping?
There's an old story from many years ago (perhaps apocryphal) about a fellow waiting in the 10 items or fewer line at the supermarket. The guy ahead of him keeps rummaging through his pockets, holding up the line. He finally states, "I know I have a 50¢ coupon for that here somewhere." He turns around partially while searching his pockets and those behind him in line recognize Bill Gates.
To be fair my husband isn’t a billionaire :-( and I can count on both hands the times he has shopped for groceries in 47 years.