Before I came to NYC, the very idea of bringing your dog into a store with you was ridiculous. I had the idea that people who brought their dogs to Bed Bath and Beyond were...well...snobs (much as I hate to admit that I thought that way, especially given my post on reverse snobbery).
Now, having lived in NYC for some time, I actually only notice stores that post notice specifically banning pets. Obviously food stores like grocery stores and restaurants don't allow pets inside, but pretty much every where else does. Bed Bath and Beyond? Yup- and I even heard one customer (with a dog) remark about another customer's dog's ability to use the escalator. Furniture stores, clothing stores, pretty much everywhere that isn't food, and you are likely to see someone leading a dog on a leash, or even carrying it (I'd say the majority of dogs in the city are little ones).
I thought about why I no longer view this as eccentric behavior. I think it's because New Yorkers taking their dog for a walk will naturally pass by stores and perhaps might combine a walk with some errands. People in 'burbs would have to load the dog up in the car, drive to the store, then take the dog inside in order to have similar opportunity.
So, my paradigm shifted.