wrote
FWIW the US does restrict foreign-registered ships and planes from
carrying domestic passengers. A Thai Airlines flight that originates
at JFK and stops at LAX to pick up more pax and fuel cannot sell a
ticket for the JFK-LAX segment. Similarly, cruises to Alaska start in
Vancouver rather than Seattle because the ships are all registered
under flags of convenience.

Eighth Freedom - This is also called cabotage and almost no country permits
it. Airline cabotage is the carriage of air traffic that originates and
terminates within the boundaries of a given country by an air carrier of
another country. An example of this would be an airline like Virgin
Atlantic Airways operating flights between Chicago and New Orleans.

Bob Moore