Airline ticket pricing nowadays depends on so any factors that it would be quite a coincidence if you met someone on the same flight who had paid the same amount for the ticket as you did. But the most surprising thing is when it costs less to go further along the same route.
For instance, someone flying from New York to San Francisco could book a cheaper trip from New York to Lake Tahoe with a layover in San Francisco and get off there, without bothering to take the last leg of the flight.
