Often some items are actually loss-leaders, enticing you to come in more often, or to pair it with a more profitable item that makes up for its cost.

Sometimes it is, even more, obvious that something is a 'loss leader'; such as at fancy dinners where they'll simply give you bread for free while you wait for your meal or bars where they give you salty snacks like popcorn to encourage you to buy more beer and not leave to have a real meal somewhere else.