TKing is not acceptable.
Well, next are statements, saying that one faction color doesn't mean one team.
Team is controllable, general players from your factions are not. In other games for being a bad "team-player" you will be kicked from the server. AOP doesn't provide "kicking" ability, so the only way is the hard way of FF.
A few misconceptions:
-Being in the same faction does not automatically make you friends..
-You are not forced to hold the hands of your factionmates.
-Looting
-Attracting unwanted attention ( for sneakers )
-Spys
Those are enough reasons for no in-faction-FF reputation penalty.
So it's up for everyone to shoot someone else or not, exactly as it's supposed to be.
Still in the same time you join faction, have access to faction chat / can communicate with different people / ask them to join them, etc, etc.