My experience of locking my ladders on my car is a funny one, though I didn't think so at the time.
For twenty years I never locked my ladders on my car. All my mates would say 'If you don't lock em you'll lose em.'
Even when one or two of them lost their's when they were locked, I still didn't lock mine. I didn't think the area I lived in warranted it.
Then one day, when another one of my mates had his bucket and tools pinched off the top his car/ladders when he popped into town for something, I thought perhaps I should start locking mine up. So I buys a D Bolt style lock and start locking them to my roof bars. Guess what.
Within a couple of weeks I came out one morning to find not only my equipment gone but my Car as well.
So much for locking my ladders up, I thought!!!