Because you don't get paid bounties for pretending to kill people. You get paid bounties for killing people. (True, in the game we bow to the "don't die without consent" convention and accept serious wounds for bounties. But still...) And game mechanics trumps RP, *every time*. If your assassin tries to "assassinate" someone, they are trying to kill that other character, not waving a rubber knife around and pretending to inflict stabbity death. And when they inflict a serious wound, it's called a "serious wound" because, you know, it's pretty damn serious. Like, you could die, serious.
If you want to completely RP an assassination attempt, then that's fine. Go ahead and do it. I've seen realms go to war over an RP'd assassination attempt. But as soon as you have an infil click that "Assault someone" link, that's no longer a pretend attack. It's attempted murder.
Well you've introduced this hypothetical of a "friend" who is also an
assassin. I'd trust my friend, who is just coincidentally also an assassin, to do a cleaner, quicker job of killing me than some stranger from another country, and also he gets the money out of it. Never said it was just for jokes, but you do see this in movies and sometimes in real life with stuff like insurance fraud where the victim has some serious coverage and a deathwish but not the guts to do it himself.
Edit: Improved hypothetical.
If you've got a bounty high enough for some cockamamie scheme like that, you're probably an Infiltrator yourself. Perhaps you're Lord of a region, you're quite old and each day is growing shorter, leaving you less time to work the trade you've mastered. You've got a knight, your "friend" who is also an Infiltrator, and whom you've been mentoring in the ways of the sneaky jerk. He's still relatively new to the game, though, without any big kills or much reputation to speak of. You know your time's at hand, so you tell him to take a shot, the final exam if you will. Even without a unit, there's a (good) chance that the attacker will be caught, since it's still murder (Or at the very least an assault). This is just one of a million possible examples if you use your imagination.
