Hacking ATMs

It is always interesting, almost amusing, to follow what thieves can come up to steal money from ATMs, POS etc. Here one of the latest stunts described by Krebs. How is it possible that the physical security of these devices is so weak? We should be good at least in physical security, since has been around for thousands of years. It is more understandable that we have difficulty in dealing with ICT security, which is a relatively new discipline, and quite complex at that.