I don't know about Washington, but California has:

(1) Candidate statements from candidates (there are requirements for being allowed to submit a statement), and (2) Pro/con statements from the official proponents and registered opponents of ballot measures (identifying the sources for both) as well as financial estimates for ballot measures (for statewide measures, these are prepared by the state Legislative Analysts Office.)

Yes, it works great. The Secretary of State's office solicits a pro and con opinion from interested groups. At the bottom of the opinion is a laundry-list of groups that co-wrote the statement. That list is often more informative than the contents of the statement itself. The booklet also includes a candidate statement submitted by the candidate for each position.

Former Oregonian here--they do that too, and it's extremely handy to have all that stuff laid out in one place. Many an afternoon I sat down with my ballot (everything is done by mail there) and the booklet and read up on the issues and voted.

The government mails out the booklet, but all of its contents are submitted by various "interested parties," and are labeled as such.