Ok, so Google has always defaulted search results to the most popular location in cases where multiple cities/towns share the same name. For instance, when a user searches for "keyword, Dallas", Google supposes that most users are looking for the larger city -- Dallas, Texas.
If the user has their geography specified (it should display in the left sidebar in Google SERPs) they will default the local searches to that city you've specified. OR, if you narrow it down further.
For instance, if I search for "restaurants in Paris", Google assumes I mean the most-popular "Paris" located in France. However, if I then make it more specific by saying "restaurants in Paris, Tx", then Google defaults it to the "Paris" located here in Texas where I live.
This defaulting behavior has been in Google to some degree for quite a few years. I expect that searches in the less-popular versions of cities may adjust their searches to be more specific, or they are defaulted to their particular city by self-disclosure or maybe if Google geolocates them by IP address.