Engineering doesn't mean all processes are flawless and surely not that all humans participating are perfect.

The collapsing bridges in the US are mainly caused by insufficient maintenance, which is not an engineering problem but a political one. And the vast majority of collapses happens with bridges that are known to be unstable and already blocked for traffic. The engineering part did that, as if it screams "told you so" at the politics which doesn't allocate sufficient funds for maintenance.