One point in defense of the airlines that people often forget. There are certain taxes and fees the airlines must pay when a passenger flies from A to B. Howe

One point in defense of the airlines that people often forget. There are certain taxes and fees the airlines must pay when a passenger flies from A to B. However, the government of location B waives fees for connections flying from A to B to C. That makes sense; the passenger never actually visited B. Passengers can find a cheaper ticket flying JFK->TPE->HKG and ditching the final leg (carry-on only). However, if an airline "knows" a passenger will skip the final leg, then they are helping the individual evade a legitimate tax.