>Why would you think that dogs that live in the city get any less exercise than a dog who lives in the suburbs or somewhere rural? Often cities are more walkable than the alternative.

You can't take dogs on the train. So if your apartment is in a nice, walkable place and you don't mind never walking someplace else in the city, then ok. But if you want to walk in a different neighborhood miles away that you need to get to by subway, then forget it; you can't bring your dog there.

I don't even know how you'd get your dog to the vet in a city, unless perhaps you can get an Uber driver to let you bring it in the car with you (not too sure about that; I wouldn't want to ride in an Uber/Lyft after someone had a dog in there, and other customers could very well be allergic, so services like this would be wise to ban dogs).