The reason speech recognition doesn't work is the same reason we don't have automated generation of novel software, automated debugging, the semantic web or any of a number of other software tools - because they all require approximately-human-level AI to provide the necessary judgement, context, extrapolation, fuzzy logic and culture. I mean, even if I misheard you when you said "balloon boy", I could still make a judgement, based on recent cultural events, that you meant to say "balloon boy". But that takes an incredible amount of processing power to make such a conceptual leap. And computers just aren't up to the task yet. The good news - the human-level-AI problem is solvable, it's just really, really hard. We will solve it someday, and it will render a huge swath of our day-to-day tedium automate-able. But today is not that day, tomorrow isn't looking so hot either.