Hate to tell it, but you should have had them padlocked.
A pal said that to me some years ago when he discovered I never locked my ladders on my car. I thought yes he's right. I bought a lock and locked them up only to get my car and all my equipment stolen together a coupe of weeks later. That was a day and a half, trying to get myself kitted out with a car and all my equipment.
A few weeks back I went out to my car first thing to find someone had cut the straps holding my equipment to the roof bars. Didn't take anything, Just cut the straps.