Because it's completely ok for officers to treat two legally armed citizens differently based on officer opinion. *SARCASM* for those that might get confused
In Oregon and Washington there is no notification law, it would be assault and battery for an officer to attack me for not breaking a law. The post above me reminds me of this post, "Great way to get yourself forcibly removed from your vehicle and experience a face plant. Expect your "spy video" and camera to come up missing when they do an inventory of your vehicle subsequent to arrest." Funny part is, most cases like this, the city plea's with the victim with this line of BS, "We will drop all charges if you don't file a claim against the city." The kind of officers you and the other poster described need to find a new job.
You're advice is not better, it's different (and in my opinion worse). I too have family in the police, and I too work closely with officers...I do not inform them of my firearm unless I feel my safety is at risk. The best way to avoid risking my safety when it comes to police? Avoid them.