Let's look at these errors, because to err on the side of under- or over-caution is costly.
It's in an FDA official's self-interest to err on the side of over-caution. People who are injured by incorrectly approved drugs — and their families — will know that they are victims of FDA mistakes, or under-caution. Their suffering makes headlines. FDA officials face unfavorable publicity, perhaps congressional hearings and possible termination.
The story is very different when the FDA incorrectly delays or denies drug approval — errs on the side of over-caution. Here victims are people who are prevented access to drugs that could have helped them. Their suffering or death is seen as reflecting the state of medicine rather than the status of an FDA drug application. Their doctor simply tells them there's nothing more that can be done to help them. This kind of FDA victim is invisible.