I returned to the server over the weekend, and the reliance on robbing players really stood out to me. So this is a great amendment to the ruleset. Although, I feel the wording and interpretation of rule could be improved. There's been many times, as still a new player, an experienced player has ran up to me with his gun and then put it away because he saw "new player". That's how I realised how much of a problem this was -- in my first couple days of playing.
The intent is good, however the wording leaves too much room for interpretation. There should be outlined places where exactly robberies cannot happen. Just saying "populated areas" does not suffice, as everyone's definition of this will be different due to there being no NPC's around to differentiate from areas that would usually be populated.
Furthermore, there should be a limit on how many times a day you're able to rob other players. As regarded in the post, some players use player robberies as their main source of criminal activity - this should not be a thing. Maybe adding a limit or 3-5 player robberies a day, on top of this current rule adjustment, will help tip the scales away from the constant amount of robberies that happen on the server.
I will say, however, the server has a lot of potential. The script is really good, and I'm having a lot of fun playing with friends, and other players on the server. If we can iron out a few of the rules, and the "cops and robbers" feel to the server. You could have yourselves an RP server that pioneers the way forward for roleplay on GTA V.