Cost of flying and regulation aren't the only factors, and indeed may not be the major ones.
Availability of cheap airfares & package deals - take the family in comfort, get there quickly, rent a car or use public transport at the other end vs. hiring an aircraft and taking many hours/days, cramped conditions, limited to no transport at the other end etc.
Road and public transport improvements - drive in comfort on freeways and major roads, stop off at places on the way etc.
Such things pass the wife & family test over hiring an aircraft.