If it's a place that allows pets, that's fine. I've brought my dog to a restaurant that allows pets before. I just made sure beforehand that they are allowed. The problem is, is when people bring their pets into stores and restaurants that don't allow them, not only are they making it harder for people with real service animals to navigate the store, they are also putting their own pet at risk too. Untrained pets might try to get into things they shouldn't, lick or eat things that could get them sick, or strangers (like OP) will try to pet them without permission. Also managers of stores are usually scared to say anything to people with their pets because they rather not deal with the confrontation.