I'm a bit out of my depth here, because it's been a while since I lived in the South Pacific.
I was suprised when Aloha added Rarotonga. I could see some local traffic from the islands to Honolulu, although most Cook Islanders would graviate to New Zealand.
And I wouldn't think there's a huge amount of tourist traffic from Honolulu to Rarotonga.
I could easily be wrong.
However, since Pago-Pago and the American Samoas are US territory I can see why there's a lot of traffic to/from there - many Federal government employees.
I think there was an airline (Air America?) that flew frm LA
to Pago-Pago, but that may have been an occasional, unscheduled flight.