I have a simple way of looking at these things - if it's not explicidly forbidden - it's allowed. Just like smoking. Every store has a sign on a door that there is no smoking in there. Fine. I comply. If there is NO sign that says "NO PHOTOGRAPHY" - I see it as I can take pics. If someone comes up and has a problem with it - I politely say - "I'm sorry, I must have missed the sign that says "No Photography". Could you please point it out for me and maybe even place it so it can be easlily seen?" Since most of these places dont have such a sign or policy for that matter - they usually let me take photos. If someone gets nasty - I'll put camera away, ask them for their full name, email and phone number for the company's home office and name of their boss. This usually makes them reconsider their position. Key is - be polite, but stand your ground. Be smarter than them.
Funny enough, I had a chance a few years ago to take several visiting dancers to a local shopping mall to do some shopping. Me and 12 girls. All beautiful. All running around like kids, taking pics of everything. Sure enough some idiot called security. Well, two mall security guys, once arrived, ended up being in the pictures with the girls and all had fun. So, I suppose it depends on who and when and how. 😉 (and I have pics to prove this 😉 )