While it is possible for someone to take such calculated risks, that is almost always /not/ the case. In order to do the calculation, you need to have at least some clue about the nature of technical problems than plague you.
Josh's examples make it quite clear that, those clients at least, use duct tape just because that's the limit of their abilities. I can't count the times I've heard "no time to do it right now, we'll deal with it when we make it" as a euphemism for "we're grossly incompetent and in any case I'd like to change the subject now". It is especially telling when a forced cut-all-corners implementation could be fixed in a couple of days, yet it never seems to make it into the TODO list until after it's caused downtime and/or major customer issues for a couple of months. Spending money based on What Idiotic Idea of the Week magazine suggested and ignoring blatantly obvious needs like reliable and verifiable backups also speaks volumes about whether such startups are actually making rational choices.