RealHJ

There are multiple daily HNL-LAS flights on HA A330s and 767s.

DL couldn't compete with HA on frequency (choice of morning, afternoon or overnight flights back or forth) or on service (HA provides a hot meal even on those short 5 hour flights, DL gives absolutely nothing even on 10+ hour flights such as HNL-ATL).

So, DL just isn't able to compete with HA, as its brand recognition is poor (it's not NWA anymore, and regardless in HI everyone thinks of HA first), its service is subpar (at least in Y), and it would need to have at least several daily flights to compete with HA on frequency and to allow for a choice of arrival and departure times. Also, even though HawaiianMiles is a horrible program with truly horrendous redemption rates (it's always been my nigtmare that DL SlyMiles may devolve into something that bad given enough time), most of the pax on the route will value earning HM a lot more than DL SM, since they get HM through their credit cards, bank relationships, grocery shopping, and countless other channels already.

HA and DL seem to agree not to compete on more routes than they compete on. E.g. HA left HNL-FUK to DL and DL alone and cancelled that route a few months ago. DL has chosen not to compete with HA on HNL-SDJ or CTS-HNL, though it easily could given the demand that is there.