Big Dogs in Apartment Building

Okay so the rules state 30lbs or under but everyone has a big dog. At first I thought it was seniority and this was a new rule but my neighbors just got a husky today and the apartment manager has no problem. In my contract and on the pamphlets it says that it has to be 30 lbs or less. I want a dog and prefer big dogs. Everyone around me has them and I was wondering if it was okay for me to just go ahead and get a big dog. I want a shelter pup and they all are large right now and I've been avoiding getting one because of the rules but I'm starting to see how it doesn't seem to matter. Why is this going on at my complex first off and second would it be okay for me to get one? Would you see it as unfair if my new neighbors got a big dog with no problem and I would get in trouble for it? Also is it unfair to have the rule in the first place if literally everyone has a big dog? Any input on this is much appreciated.