You may have an alphanumeric postal code but as far as I'm aware there are no alphanumeric ZIP codes.
https://en.wikipedia.org/wiki/Postal_code#Alphanumeric_posta...
If I'm askimg for a ZIP code I probably already know I can't deliver to you. If I thought I could deliver to you I'd collect the data necessary to do so, though not by asking you to pretend that the meaningful differences are not meaningful.
Others operate differently, Amazon makes a bunch more revenue than me, YMMV.