You're probably right. It's pretty surprising how many people don't know their own address. And I don't mean typos. Completely wrong zip codes, missing suite numbers in a huge strip mall, wrong city, no business name when that matters, etc.

The best change I made was having them first enter zip code, then pick city/state from a list that goes with that zip code. Both Google and the USPS have apis for that mapping.

Also, fun fact: UPS charges me $15 if they have to make an address correction at delivery time. So, for example, if a customer fails to put a Suite number in, and the UPS software doesn't tell me it's missing, UPS charges me $15. I've complained that I shouldn't have to pay when their software fails. They don't care. Argh!