One option is staircases (aimed at reducing mass casualty events in fires). There are other options to improve fire safety. There are other options to improve safety in other circumstances.

Perhaps with the costs of second staircases, there are things we could do to buildings for less money that would save more lives from fire. Should we do both? Just the cheaper one? Neither?

How do we decide which ones are justified for their cost, and which ones aren't? Who should bear these costs? What things should be grandfathered and have a slow transition towards higher safety? What things should be immediately improved?

The answer to the staircase question comes down to how we answer questions like this. And the fact that we may be tolerating much bigger risks is definitely an interesting point.