Psychology is inherently a part of this. As other commenters upthread mention they calculate things in terms of relative security and "it will take X time to br

Psychology is inherently a part of this. As other commenters upthread mention they calculate things in terms of relative security and "it will take X time to break my lock, but 1/5 or less X time to break the lock next to mine." But that neglects the perceived value of the secured asset. If your bike is worth quite a bit more than the poorly locked bike next to it, it can be worth the extra effort and risk of stealing it. Similarly for storage units, if a thief has unimpeded access to the place and only has time to try one or a handful of units, the unit with the beefy lock probably indicates more valuable stuff inside than the unit with a normal looking lock.