This whole subject is like a bad penny that keeps turning up.
I don't like "suprise" guns on a traffic stop. Traffic stops are a very dangerous place for cops. I appreciate being told about the gun and just tell people not to put their hands near the gun. I ask for their pistol permit and make sure they are legit to own the gun, then send them on their way.
I would never ticket somebody just because they didn't tell me, but I have let people go because they did. Take that for what it's worth.
Routine traffic stop, turns into a shooting.
Cops see a gun they are not told about, they are going to be concerned for their safety.