the bit about charter can cancel a flight is not true the airline has a contract with the tour operator and would be heavily fined if a flight is cancelled.whereas say easyjet only had 1 pax they can cancel a flight and rebook that pax on the next availible flight.and many charters only fly once a week from smaller airports whereas easyjet would have a flight a day if not a few a day so less disruption to that 1 passenger.