I don't think anybody can give you the right answer on to why Jagex gives out 2-day bans. What makes sense to me is usually older accounts with quests, a majority of skills leveled, often doing different skills and typically not gold farming... will receive 2-day bans. It makes sense right? Well, I have had a ton of random gold farming accounts get 2-day bans whereas accounts I was not even farming gold got a perm. Luck of the draw maybe? Or Jagex just doesn't make sense.