At a more general level, your mailing address indicates how to deliver your mail; it does not indicate what city, if any, the delivery address is in. Neither does your zip code (as illustrated in the article), your phone number area code, or phone number prefix. All of these things indicate the location of the mail or phone facility that services the delivery address -- or that once did, before facility consolidation or expansion.

A related phenomenon is that different agencies have different boundaries, despite often sharing the same geographic name. Cities, water districts, sanitary districts, school districts, community college districts, counties, congressional districts, etc each have their own boundaries, and they are usually not aligned.