I think the problem may be that "order of magnitude more" means different things to different people. Colloquially, it does get used to mean "a lot more", and some people use it because it sounds more scientific. But in a more correct sense, it means "closer to 10x than 1x or 100x": https://en.wikipedia.org/wiki/Order_of_magnitude#Definition.

I personally dislike the phrase and try to avoid it. But if one is going to use it, I think it should be used correctly.

(I agree with jdietrich that the definition of "city" matters)