I never put gun stuff in anything other than a range bag, and I never take range bags traveling. I don’t understand - are these people using their travel luggage as range bags? I can’t say I’ve ever seen someone at the range unloading ammo from a suitcase.
Your situation is a bit different, though. You’re actually driving across the border. I can see accidentally leaving some range gear in a vehicle, and especially ammo if you tote it separately as you might with rifle or shotgun shooting. Your diligence is commendable, and wise considering you’re crossing one of the two borders we have.
Ultimately, the only person I trust with a firearm is me. It sounds as if you’re more charitable than that, but we agree there are a lot of people who really shouldn’t have guns.