I would say that most FW bugs are found in the years that the car is under warranty (At least 2years here in EU) - which means that you have to (there are some new laws around this, but there's no change to be seen in practice as of yet) drive it to a certified mechanic/dealer that has the equipment to update the FW quickly (there's a big chance that he will have the car connected to the diagnostic equipment anyway). And the bugs/updates that are missed this way usually get solved when the driver notices them and drives them to a garage (around here the mechanics, even the non-certified ones have quite a good grasp of common faults that can be remedied with a FW upgrade). So overall this isn't as big of an issue as someone would think.