• What are we protecting? How much is it worth? In some of the earlier examples, designers didn't consider what was important, or atypical but catastrophic failure modes. Among others, Bruce Schneier has repeatedly asserted that airport security focuses entirely on the wrong areas, looking for the threats we've already experienced rather than assuming an innovative adversary.
• What is the threat we're concerned about? Is it a natural phenomenon, an attack, or an accident? In the case of voting systems, are we worrying about wholesale theft of a presidential election or retail theft of a local precinct? Were the Russian spacecraft designers considering the threat of nuclear radiation, software malfunction, or both?
• What are the costs of the protection? Are we throwing the baby out with the bathwater? This is where not only privacy but also convenience fit in.