Quite simple really, because it costs alot more to operate aircraft at the sort of times when people “want” to fly. Scheduled airlines will be able to manage it, but on the whole they will charge alot more for their tickets.

Charter airlines are much like low-cost airlines in the sense that they need to maximise the utilisation of the aircraft during the day so that it reduces the amount of time they spend on the ground sitting around doing nothing, hence why you have such early departure and late arrival times.