Well, you could try and balance credits earned per time period between various ships, with all other variables very similar. The Beluga is cheaper than the Anaconda, though. So it being noticeably worse would make sense, I guess.
Anaconda is a multi purpose ship that excel in combat (PvE rather than PvP), exploration, trading.
Kruger's ships are supposed to be the end ships for making profits with vip passengermissions.
For now passenger missions that pay the most are economical and business class.
First Class and Luxurious class passenger mission pay really low compared to them.
First Class cabin should be limited to luxurious ships : Kruger's ship and Cutter/Clipper.
First class and luxurious mission should pay a lot more than economical and business.
This seems logical.
For now there is absolutly no hierarchy and no logic in passenger payment. Exception to situation of war in some system were refugee pays a lot to flee the system (economic class) or because you transport prisonneer and you are going to be attacked along the way to your destination.
Again Multi-role are good at everything and this is really stupid. Hauler should be good at hauling, Passenger ships should be good for luxurious passenger trip...etc.
In our real world you are not going to transport goods with a battlecruiser even though it has huge space, speed and huge defense... because it's gonna cost you so much that you'r gonna make no profits at all.
Current logic is to make you slowly grinding for better ships... But at the end, with easy money you can make now and in the past you still end up with all the ships and no possibility to have good role play because ships are not specialized enought.