Ask. Next time you want to take photos of products and displays, ask. Twice yesterday someone, a middle-aged male, walked around my newsagency taking photos. The first time as I approached him he fled. The second time he fled when a team member made eye contact with him.
If I take photos inside another shop I ask and if there is no one in authority to ask I do it openly. This guy was being sneaky, holding his phone camera close to his chest, positioning himself with his back to the counter where he could. He was photographing gift products and displays.
We get plenty of visitors and the majority ask if they can take photos and we agree.