In some countries it is actually illegal - the way he put his camera down I wonder what the law is there. I know in the UK there is no law against it, but my last visit there (which was a layover basically so very brief) I asked before shooting and was told "no" in some cases. Being a foreigner there, I did what I was told so as not to get into trouble and miss my flight (or mess up with work - I was on a biz trip and frankly that was my biggest concern).

Later on the same trip, I was in India where railroad photography is 100% illegal. I managed to get some in with some local railfans. They knew where to go that we wouldn't be hassled and told me when to hide my camera and when it was safe to take it out. It was great to have them help me and without them I wouldn't have bothered trying. Would have been insane to try. I would have gotten myself arrested.