Q for my service industry peeps

Last night I was walking to Peabody Place to get some money out of the ATM, and on the way there I ran into a friend of mine. She was working as a server for a new restaurant downtown, and was outside taking a smoke break. We talked for a few minutes, and as she started to walk back in, another server came out to smoke. “Why didn’t you come get me before going outside?” asked the other server.

“We’re not allowed to smoke together,” said my friend.

That seems like an odd rule. I’ve never worked as a waiter or bartender, but it seems to me that if I were a business owner, particularly in a business with a high turnover like restaurants have, that I would want my employees to socialize (provided their tables are taken care of first). That way, they’d develop relationships at work that they wouldn’t want to lose, and they’d be reluctant to leave and take other jobs.

Just curious, what’s the reasoning behind a rule like this? Anyone know?