Clearly if you are in an earthquake zone then earthquake protection are high on the list. If you are on a flood plain, then flooding needs to be managed send so on.

Now for my next part, I run the risk of being flippant. That's not my goal. Clearly the building code failed those 115 people, and their loss is 115 families in mourning. But, and I say this with all due contrition, that "only" 185 people died is a measure of regulation success, not failure. One building collapsed, but most survived (at least enough for people to get out safely.)

No doubt that building will be learned from, and there will be efforts to make every building perfectly safe. As you point out some building may be too expensive to rehabilitate.

Should those buildings be demolished? It's easy to count the dead from one gat fell down. It's harder to count the deaths from no-building, or a demolished building.

Obviously in an earthquake zone, earthquake regs are critical. No argument there.

But what about a million small regs that add up to real cost, but offer minimal gains? Each seems, in isolation, to be Important, but their collective protection seems marginal.

Again, it can seem cavalier to say "good enough", when "perfect" saves lives. Its easy to count lives cost with "good enough". It's harder to count lives lost to "perfect".