They are in no way equivalent in relative ease to quantify. Safety Regulations exist to protect from "known" harms. It is the result of learning from our past and applying that knowledge to our present and future. But anything in the unknown harms category is fundamentally unquantifiable. We know there are unknown harms out there. But we don't know
1) What they are
2) When they can happen
3) How many they could affect
You can't make decisions that help you avoid harms in that category. But you can make decisions in the other category. There is an argument that failing to build is for example in a category of known harms now. But so are a whole host of harms that we encountered to get where we are now. The trick is to make it easier to build while not also engaging in the rest of the known harms out there.
>But anything in the unknown harms category is fundamentally unquantifiable
The "unknown harms" exist in workplace deaths. In fact many of them come from such factors. It's not just things like "asbestos is bad to work with, you need a face mask and other protection" or "construction debris might fall, workers need to wear a hard hat" and such, but also things like materials breaking under unforseen circumstances, unforseen disasters like earthquakes and fires while on the job, and more...
1) What they are
2) When they can happen
3) How many they could affect
You can't make decisions that help you avoid harms in that category. But you can make decisions in the other category. There is an argument that failing to build is for example in a category of known harms now. But so are a whole host of harms that we encountered to get where we are now. The trick is to make it easier to build while not also engaging in the rest of the known harms out there.