In an era when Skype is available to interview job candidates, the need to meet in person remains. Shaking someone's hand and looking them in the eye can tell you a lot more about the person than talking on the phone or seeing them on Skype. If the company is serious about investing in a person, it will want that person to fly out.
But the economic impact of a 9.5 percent national unemployment rate, results in employers having their pick of the job pool, and even asking potential employees to pay their own airfare so they can press the flesh. Paying $500 for a flight, and possibly a hotel, can leave a large dent in your wallet, and a more painful one if you don't get the job.