A camera+OCR would be so painfully less reliable than a QR code or even a traditional barcode, either of which could represent a short string that could contain a power level, heating/standing times, and wait characters (like the special pause/wait characters traditionally supported by cell phones). It would take some hefty marketing muscle for a manufacturer to get the ball rolling for including this on food packages, though. Perhaps there's a professional organization within the food/appliances industry that could make this happen.
It would "just" require a manufacturer to offer a sufficiently good partnership to a handful of the largest supermarket chains. The large ones like Walmart, Carrefour, Tesco etc. have more than enough market power to simply tell their suppliers they'll suffer from marketing favouring their competitors if they don't add labelling following a certain standard.
