Some of their friends might not be willing to hack it themselves for one reason or another, but will have no issue taking the ill gotten gains from someone else. You see it all the time in GTA V. It's hard to play that game online and NOT have a hacker give you millions. I don't want that for Elite.
In GTA V it's not friends but utter strangers giving them away. Given how hard one has to try to end up in a wing with someone to begin with, let alone newcomers who have little idea of the game, the mechanics alone make it much harder in Elite (and thus less fun than in GTA V) to throw around with money. You don't go and throw it onto his windscreen, or you wouldn't. No matter how, I'd be sure FD would come up with some overly complicated mechanism just because.
Just pretend:
(>Be friends in-game)
>You have to be in a wing
>You have to be in the same instance
>You have to successfully send and accept the trade invitation.
Even I sometimes miss such cruel points as friend invitations thanks to the subtle HUD (which I like, mostly). It really would be the aimed transaction that would come to E: D, namely gold sellers or friend boosters. It's just not the game for people to drive around and throw money at people. As it is most people expect griefers when they see random people coming for them already, lowering the chance for hackers to throw random money around even more.
I just can't see it hurt E: D so much that it can't be in the game. I just can't.
Edit: Or even better, let the transactions only happen via CQC modules. It stands outside any immersion anyway, so that goes out of the window. You wouldn't find spam inside stations since you can't trade inside the main game. People would have to be friends and manage their bank accounts (credits!) where they also can earn credits for the main game, without playing it! How would that hurt anyone?!