Why do I see fire trucks at the grocery store?

Because the firefighters work a 24-hour shift, they eat and sleep at the fire station. The firefighters pay for all of their own food, and sometimes bring food from home. Occasionally they need to go to the store, but they are still on duty. They do not have the freedom to go anywhere alone because they are in constant emergency response mode, and must stay together with their team and their apparatus -- ready to move out at a moment's notice. If you pay close attention, you'll notice that they are carrying emergency pagers and radios. Sometimes they get a call and have to leave their items as they quickly move out toward the emergency.