I fail to see how you can claim this to work for sites which serve areas outside the United States, but have either no ZIP code, an overlapping code, or something else entirely. Germany has 5 digit PLZs, but putting some valid ones in doesn't get a result. It really seems like the author does not think about other countries.

I don't disagree with reordering the entry by relevance, but you have to start with country. That can also be a nice search - it will be a very short lookup, even if you put every country name in every language. Only after that is postal code (of whatever kind - it's only ZIP in the US) relevant.