In those cases, there are change rooms or locker rooms. Just like in grade schools, you had locker rooms and lockers.Why? This is true in many industries. Can't bring in any personal electronic devices for security reasons. People who work counting cash and coins can't bring any money or even metal to work. Medical transcriptionists and bank call center workers can't bring any paper in or out of work.
Or safety reasons: bags can get caught in moving machinery or get sucked up by a jet engine. Or economic reasons, you drop it on a wing and make a $250k dent...