You are correct, private property can be a public place. Stores are a definite example of this. Many people get very confused by what Private Property! means. B

You are correct, private property can be a public place. Stores are a definite example of this. Many people get very confused by what Private Property! means. By inviting the public into their store they have waived the requirement to have privacy in that space, unless they specifically inform you that photography is not allowed. The irony is that the visitors to the store can have no expectation of privacy. Even if you wear a giant sign that says 'no photos' you can and will be photographed. Publishing photos of specific individuals is more nuanced. It depends on the jurisdiction, if it is for news, artistic or commercial purposes (the latter is usually forbidden without written consent).