Nobody knows their +4 code. You cannot ask for information 90%+ of people won't have.
If asking for the zip first was more common then we quickly learn those four extra digits because the auto fill benefits would be immediately obvious
10% of the US population is 35 million people. That's a pretty weird version of "nobody".
Of course they do.
Let me uh just grab my utility bill...
If asking for the zip first was more common then we quickly learn those four extra digits because the auto fill benefits would be immediately obvious