I think you're missing my point, sorry if I didn't explain it well enough. Science tells you that, unless you wish for it to fail, a bridge needs to be strong

I think you're missing my point, sorry if I didn't explain it well enough. Science tells you that, unless you wish for it to fail, a bridge needs to be strong enough to withstand gravity, wind etc, what the stresses are, how likely it is to fail given XYZ conditions, etc. Politics has you advocating for bridges to meet minimum standards under threat of legal sanctions, deciding what those minimum standards should be (one failure per 500 years? 5000? etc). They are different things. You cannot decide scientifically how many resources are worth spending on safety, value judgements are required. To put it another way - science can tell you how to build a stable bridge. It can't tell you whether you need to build the bridge in the first place, or whether one stable bridge is a better use of resources than three mostly-stable bridges.