Lots of people don't understand how colds spread. Each common cold virus is different and everyone has a different immune system. There is a good chance that your immune system can combat another person's cold. But the biggest factor is the fact that most people are contagious BEFORE they develop symptoms.

That doesn't mean that you should go to work sick, it just means there are better things to spend time complaining about since you are just as likely to catch a cold from the thousands of people who interact with at the airport than you are from that captain who sneezed in the flight deck.