Earlier quoted context omitted.
Does this mean those places also ban people from using smartphones or normal cameras on the premises? There is no indications that Mann was actively taking pictures of strangers. And it would makes sense for a tourist to take pictures of his family at a restaurant. How are tourists normally treated when they try to take pictures of their vacation?
yes, basically if you use your smartphone to take a photo of a dish, they'll complain about it.
But the spirit of bambax' and others' messages is true: in Europe, customer is not king and should behave in a way that pleases the shopkeepers or restaurant owners. This is more true the closer you are to the capital or the city's hot spot.
And more generally, one has to develop a sense of what is right in a particular place, not assuming that the same customs apply as in your home country. Americans don't have a good record at that, I'm afraid. As someone pointed out, you're bound to inadvertently offend people, but rushing into a place with a camera is a good way to start learning from your mistakes.
That being said, the violence displayed by this particular personnel is completely over the top and should not be tolerated, not by customers and not by law.