Isn’t UA flying lie flat F to Hawaii mostly an operational consideration, where it simply makes sense for them to route an internationally configured bird to Hawaii on certain flights and/or seasonally for a variety of reasons, largely related to fleet utilization and capacity (of course with ETOPS constraints)? I don’t know UA well, but certainly that’s the case with AA. When you get a lie flat seat on a route that doesn’t always have it, it’s marketed and priced as domestic First (or regional Business in the case of Caribbean flights). AS using Airbus planes in the VX configuration is basically the same but the fleet is the way it is for a different reason.

As with transcons, that doesn’t mean you shouldn’t take advantage of it when you can. But UA isn’t making fleet or pricing decisions based on putting lie flat seats on Hawaii flights (or any flights other than the premium transcons and long haul international), are they? Of course, AS has no long haul configurations, so in the long term they won’t have a better F product getting subbed in for operational reasons.