99.9% of web search forms that ask for a city accept a zip code, and are often more accurate when doing so, as even a mid sized city can be composed of dozens of zip codes, never mind places like Central Manhattan where some zipcodes resolve all the way down to single buildings.
...but this page is part of the 0.1% (by your math) that actually wants what it asked for. So, this is just a case of user error. Enter what it asked for and it works great.
Harrison Township, Michigan goes to Harrison City, PA. I then tried the city to the south - Saint Clair Shores, MI and that took me to San Antonio, Texas. I'm working in East China, Michigan and that took me to East Chicago, Indiana. I ended up just using Detroit, MI to get anything useful. So, no, that doesn't work either.
