"it's impossible to ship perfect software."<p>That is simply not true.<p>It may be very difficult, it may be insanely expensive and it may require an immense effort to thoroughly inspect the whole stack that is under the software (down to the hardware level, that is, with some attention on how external events may influence the hardware) but no. It's not impossible to ship perfect software, specially if you restrict the definition of "perfect" as doing what it's supposed to do, no more and no less.