I don't think we should set our expectations based on an extreme outlier. qmail is special, and we can't expect most software to get to its level of security/safety.
Put another way: if you have to rely on programmer skill or attention to detail in order to guarantee something, that will always be a losing bet, on average. The existence of a tiny percentage of programmers that can clear that high bar does not make it a valid strategy.
Put another way: if you have to rely on programmer skill or attention to detail in order to guarantee something, that will always be a losing bet, on average. The existence of a tiny percentage of programmers that can clear that high bar does not make it a valid strategy.