Last night I was stopped at a red light, idly twiddling my thumbs waiting for the light to change, when we (me and the two other moped/scooter riders) see a little old lady jaywalking against the light. Not entirely notable, since jaywalking is one of those little crimes that everybody commits, but then she walked up to one of the scooters next to me and proceeded to say something along the lines of, "My bike was stolen and the thief went that way!" She then climbed on the back of the scooter and the guy took off in the direction she was pointing in.
I sincerely hope she gave the bike thief a good purse-whomping.
One of the little-known, less-bragged about facts of life in the Netherlands is that bike thievery is rampant. You wouldn't think so, given how orderly life is otherwise, but the fact is most bike locks are crap and even the best won't deter a thief hell-bent on mischief.
One of the still-lesser known facts of life in the Netherlands is just how much a good bike can cost. You can have utter pieces of crap for €50--I've bought one, and rode it into the ground. A good new bike can easily set one back €500, and usually costs even more. Even a used bike runs up to several hundred euros, so it's understandable why people get so upset when their bikes get stolen.
An apparent contributor to this problem is, apparently, that very few people in the Netherlands actually know how to lock a bike. It is astounding how many people lock their bikes with a simple cable-padlock combination. Cables are by far the WORST thing you can use to restrain your bike--the thinnest ones can be snicked with a pocket knife, and the thicker ones require only a small chainsaw. Most people have a little c-lock, one that's attached to the bike at the back and is locked and unlocked with a key. Such locks are pretty good--you can't easily bust those without busting the bike--but not foolproof to anybody who can pick a lock. I've had my bike lock picked--my bike was moved, but not stolen. Chains and u-locks can also be broken with relative ease, but these require time--on the order of 20 minutes.
There really is no way to prevent a thief from making off with your bike if he really wants to. Which is why the best way to prevent bike thievery is to prevent him from wanting to. Breaking locks is not a quiet endeavor, and it can take a long time, so parking your bike where someone is likely to hear the sound of a snapping lock. And putting on multiple locks, which might seem like overkill, is also useful--it means that a would-be thief needs more time to break them all, time which he won't have if he's just pretending to be a guy who's got a stuck lock. I have 2 locks on my bike, but I'm never under any illusion that either will be useful against a determined thief. Really, all you can do is increase the odds of having a thief get caught in the act.