In the Star Wars movies, an entire enormous imperial military mechanism can always be destroyed or brought to a standstill simply by targeting some relatively small but apparently crucial component a shield generator, a droid control ship, an exhaust vent on the Death Star.
Id like to think this was George Lucass deliberate satire on the rigidity and inefficiency of centralised bureaucratic systems though I have a sneaking fear that it may just have been lazy storytelling instead.
In any case, Darian Worden points us to yet another real-world example:
On Sunday, January 3, thousands of airline travelers were delayed after an unknown person walked the wrong way through an exit at Newark Liberty International Airport. Continental Airlines, the largest user of the affected terminal, was still behind schedule on Monday morning. … Most Americans depend daily on the functioning of a multitude of networks, from transportation to electricity. The Newark shutdown shows that something as minor as passing the wrong way through a door (from the public area to the sterile area) can cause a cascade of failures as flights are delayed, connecting flights are missed, and important business and personal meetings are disrupted.
I remember a similar incident at the Atlanta airport four years ago as I was waiting for my flight to Prague; someone went up the down-only stairway to retrieve something theyd left behind, and the folks in charge responded by shutting down most of the airport though thankfully not the international terminal, so I didnt miss my flight. (That incident probably did play a role, however, in our leaving late and my nearly missing my connection in Zurich; Ive spent a total of fifteen minutes in Switzerland, and all of it running.)
Remember how one Christmas light burning out always made the entire string go dark? Notice how they dont make em like that any more?
So why do governments design systems that can be jammed so easily? Well, because theyre a monopoly, so they can externalise the costs of this crap onto everybody else. Just try doing the same thing under free competition.