You can also Roleplay without PvP or hostility, but you are correct. Many people like to PvP. That's why most trading factions have a department or similar for escorting. So, in trading factions, RP can include PvP.
What's boring about trading? (F2, F3, Thrust, F2, F3 <- That is not an answer since the same can be said about PvP; EX: MouseClick, thrust, reverse, strafe, thrust, reverse) I can interact with everyone in my path, shoot a hostile trading corporation or pirate or freelancer, etc. Also, in a convoy it's all about tactics and orders (just like PvP).
Also, trading is not the only way to make credits in Freelancer. An example in my faction is that we pay people in our Social Services Office to basically Roleplay with others in the game. The most someone has made so far in one assignment is 45 million.
So, what are the big differences between a trading faction and others? Is it really just the PvP differences?