My guess, though it carries a bunch of other problems that people below listed:
Population density means zip codes are extremely concentrated in NYC, especially in Manhattan. Traveling down the length of Manhattan might have you cover ~25 zip codes in 13 miles. Basically, a zip code isn't a meaningful measure of distance like it might be elsewhere. A radius might also place you into NJ, which could be an issue depending on what you're trying to accomplish: Delivering something from Queens might be significantly easier than from NJ, even though Queens might be further.
That's my guess anyway, though it's odd because nowadays generally looking something up via zip code + radius is actually easier in Manhattan (with a map you can easily see whether it would require coming from Jersey, crossing the park, etc. etc.)
Population density means zip codes are extremely concentrated in NYC, especially in Manhattan. Traveling down the length of Manhattan might have you cover ~25 zip codes in 13 miles. Basically, a zip code isn't a meaningful measure of distance like it might be elsewhere. A radius might also place you into NJ, which could be an issue depending on what you're trying to accomplish: Delivering something from Queens might be significantly easier than from NJ, even though Queens might be further.
That's my guess anyway, though it's odd because nowadays generally looking something up via zip code + radius is actually easier in Manhattan (with a map you can easily see whether it would require coming from Jersey, crossing the park, etc. etc.)