It's real simple but first you gotta learn English. For example "CA" in an address DOES NOT mean California. Why are you PRESUMING that it does? It's a POSTAL ZONE. The official abbreviation of California is Calif. So when gov't agencies send you a letter to "CA", they're NOT sending it to California but to some FEDERAL ZONE.

On top of that ZIP codes are NOT required for first class and priority mail so why are gov't agencies requiring it when they want your address? OBVIOUSLY to establish that you're in a FEDERAL ZONE where they have jurisdiction, and NOT in a state of the Union where they DO NOT have jurisdiction.

Just try to get some gov't benefit by insisting that your address has no ZIP code. IT CAN'T BE DONE! Why? Because they have no jurisdiction outside of ZIP codes!