The people at my gym won't share a lane either - usually it's not needed, but when it is, it just won't happen. (unless I'm there with friends and we just take over a lane to ourselves). The other day, I had one lane and noticed somebody come in and sit on the bench. Since the other lanes were full, I asked him if he wanted to share, and he looked at me like I was crazy and proceeded to sit there for 45min waiting for someone to finish. And he was there with a wet suit, and appeared to be a triathlete!