But they're already dead, so future events do not affect them, as they are no longer in the iterated game of life.

The engineer, on the other hand, continues playing the iterated game of life, and so their reputation does matter (to themselves at least). Therefore, by making sure that any bridges that collapse has social stigma painted against those who designed and/or built it, it would encourage proper engineering even if there's no third party at the time to certify it.