Elastic versus inelastic demand.
Travel by car, cigarettes, beer (in my case, at least), the consumer will pay a lot more before reducing consumption.
Airline travel, grocery produce, beer (for most other people), the consumer will wait for a sale or do without.
Economically its not quite that simple, but you get the picture. If somebody made airline travel as addictive as crack and cut back the supply slightly, we could sell seats for $2000 apiece.