So, as the title says, here are a few ideas on how to make Liners a little more common in-game.
At the moment when I see Liners, they're mostly some sort of Fleet Jewel for factions. Which is pretty cool. But I don't see any Liners actually do what their primary function should be, transporting people around Sirius.
Maybe if we add a bonus for Liner Transports they would be more common. For example, at the moment VIPs take up 5 spaces worth of cargo, but maybe if the player is using a Liner the cargo space goes to 3 or 4. Something along those lines...
Don't know how FL is actually coded but if you make a variable when purchasing Human Cargo, then change the value of cargo space it should be fine?
If you think about it the RP reason is simply that Liners are actually built for human accommodation, but industrial transports aren't designed for that.