Long distance passengers need separation
Payment for long missions is meaningless unless you want a "reason" to go 12,000ly and back again. Even mining gets a vastly better cr/hr than long distance passenger missions.
So why are there no "Thomas Cook, 3300AD" companies looking for people with Belugas or Orcas or Dolphins and asking for a lucerative passenger mission to Colonia or the 34th century's answer to The Wailing Wall? The best way to make the cr/hr decent is to fill your passenger liner, but the system only puts a half dozen people who demand the entire 32-berth cabin to themselves, to twenty different locations.
Those missions are explicable for someone who just puts some cargo space to one side but otherwise are doing the mission for something else. Not so much for an owner of the premier line of passenger ships. If you could pre-book your passengers, you could shop for a full load, but the games' design requires you take on passengers right there and then. Making the "You have 7 days to complete" rather meaningless. Either you spend 7 real life days doing nothing but hanging about or you do this one single mission, leaving most of the point of anything bigger than a dolphin moot.
It should be possible to play as full time bus driver. Currently not possible.
Mind you, it's a real grind to play as full time contracted cargo hauler or independent trader too.
But this one has options to fix. One example I can think of is make MOST of the missions in the passenger lounge for the same place. If this board doesn't go where you fancy, either wait for regenerated missions or go elsewhere. But you can at least then select enough to fill your cargo hold, no matter what size your ship or passenger suites.
If the one mission for 3mil/2000ly is accompanied by 20 other missions you can fit in and do to the same (or near enough) run, suddenly you're looking at 60mil/2000ly. If the 7mil/20ly mission is the only one you see short range, you still win on cr/hr, but there was little point buying a big liner for it, and you don't get to play around in Colonia.
Plus there needs to be more one-way tourism. Who pays 3 million to go to Ayers Rock for 20 minutes? You book a flight there, spend a week or more there, then book a flight back.
Biggest problem of the long distance jobs is that you have to keep the custards in the hold, so you can't even putter around 2000ly away and have a bit of fun doing something new in a new area. At least if you dumped your passengers there, you could do something else for a bit and then pick up a new set of passenger for the long haul back.