When I bought my pistol, I had to fill out paperwork with very specific info about myself and the pistol, and then had to wait 7 days before it was mine. I don't see why everybody shouldn't go through the same regardless of where they buy one (ccw permit holders notwithstanding). It's easy to just save that background check and firearm data instead of discarding it within 24 hours.
That's firearms registration, my friend. Also, that may be the process in your State but it isn't the law of the land and definitely should not be. That is the first step to confiscation. You are S.O.L in your great State of Washington if they ever outright ban w/o grandfathering any type of "assault weapons" or specific types of firearm and you happen to have them in your possession. You will either turn it in or they will come for you.