I left my NY Fuhgeddaboudit lock on the public rack outside my office on 42nd St in NYC even though I had indoor parking. They didn't want locks left at the bike racks inside. One day I get to the office and the lock is gone, along with all the other locks that had been left there forever. I had meant to put my phone number on it but never did. So yes, sometimes they get removed. And if they can remove it, anybody can. No lock is really safe.
I bought a somewhat lighter U-Lock/Cable set, also Kryptonite, and the funny thing is I was riding over the Marine Park bridge to the beach one day and had the lock bungeed to the rack. I hit a bump, the lock popped up loose, and went over the side into the bay below. I'm on my third lock now but don't use it all that much now that I've retired.