Maybe because in free states (not sure if Oregon qualifies) it isn't required. Self defense guns are useless when locked up, and teenagers should have the capacity to not eff around with them. I've left unloaded (checked twice by both me and my wife) guns in the bathroom as a test for my kids - every time, EVERY TIME, one of my kids will tell me that I left my gun in the bathroom, and won't touch it until they've seen it cleared. This has been since they were 4. In fact, they come running to me to tell me I left a gun out when it is cased and trigger locked for hunting the next day, because they don't know about the trigger lock because they don't touch it.
Locking guns away is good for an external threat like fire or theft. Not a good substitute for training. If this state didn't require the stupid safe storage, I'd do like I did as a kid, keep my guns stacked in the corner so I could access them easily to clean while watching TV or just quick dry fire.