If having something like the zip code not be accurate, then what's the point of having the zip code in your data? People writing code to store zips/addresses are doing it to not not be able to send/verify/etc. They are doing so that the can, but if the data is wrong then they can't.

What countless applications that ask for a zip code/mailing address and don't need it to be accurate? I would then say that any that you name would actually not need the data in the first place. If your hoover it up just to sell later, wouldn't it be worth more to be valid? So again, I'm right back to why do you need it?