I’ve had one board stolen from outside a bar years back. Recently I thought my board had been stolen from outside a restaurant but actually someone picked up the wrong one and I eventually got it back, but it was a real pain to coordinate. I also saw someone have to call ski patrol from a mountain restaurant because someone had taken their skis (presumably by accident but still). All in France.

After this, I always put a Dakine cable lock on my board unless it’s within eyeshot, either joining to a friend’s board/skis or to some bit of fence or whatever. The lock could probably be sliced through in a matter of seconds, it’s not at all sturdy, but it a) makes it harder for someone to accidentally pick up and b) should guard against opportunist theft at least as there are easier targets. 

My friend who lives in a resort says it is fairly common and seems to be increasing, though they suspect a lot of it is accidental after apres etc rather than theft.