The travelers who book last minute and do not stay for the weekend, who are usually traveling for business, have inelastic demand. The travelers who book in advance and stay over a weekend are usually taking a vacation, a luxury, and have elastic demand. Therefore airlines charge higher prices to those who book last minute because they know that these travelers will still purchase the tickets, and they charge lower prices to those who book in advance because if the prices are higher they might choose a different airline, different form of travel, or to not take a vacation at all.