I don`t tend to use a tripod a lot these day, the technology with the newer generation cameras doesnt really require one for my type of photography, for extra stability I use a monopod on occasion which doubles up as a walking stick, which is something they can`t really argue about.
Well apart from the MTA staff in New York, there are other locations where even monopds are resisted, e.g., (non-rail) the Olympic Stadium banned monopods during 2012 games. I got around that with a walking stick with a small compass that when removed reveals a 1/4inch thread. All I had to do was to walk like I needed the stick when entering. As I said, for video, the use of handheld gimbals are the way ahead, even with cameras that have 5-axis stabilisation.