required or just possible documents that you can use to register?

For example, to register to vote in WA, you can do it online if you have a valid DL or state ID card. Otherwise, you have to do it by mail or go in person to establish who you are or you can do it when you're getting your driver's license for the first time. The things they list, other than fingerprints (which so fucking stupid), to not only ID, but also residency and citizenship, including items that are standalone (like passports or military ID), or other documents which require more than one supporting documents (naturalization papers, immigration documents, etc). Depending on those documents you can register to vote right then and there while you're getting your license. If you're not a citizen, you can still get a license or ID but they won't be eligible to be used for online voter registration.

Bottom line....no matter what route you take in WA, the first time you have to have some documents of some kind, but there are a whole list of ones that are possible. It isn't hard. So what exactly is the senator proposing that AZ doesn't already do?