Food handlers must wear caps and aprons

as I was having breakfast in a coffee shop in Penang recently, I suddenly noticed the shop owner sending a signal to all his stall owners to put on their caps and aprons immediately. And then I found out that he had spotted some health department officers somewhere near the shop.

This is disturbing because I understand it is a must for all food handlers to wear caps and aprons at all times when they are operating their business, not only when they see Health Department officers coming around.