Well even if you are sure about your intuition in the knowledge that this confidence by humans has led to huge problems and tragedies in the past, you still want to have a good estimate of the effect size.

How much resource to allocate to this treatment vs other treatments having a positive effect.

Somewhere there ends up being a trade off that I will caricature as "Do we want another hospital OR another park?"

(All the above is idealised, the biggest win that moves the efficient frontier outwards is effectively fighting corruption and being vigilant defending the gains made. This seems to be universal across countries and cultures).

> I recall seeing some fairly befuddling ones, like "Study finds that being in a green environment with plants & flowers reduces depression" etc., how do you even quantify this into numbers?

"Effects of things on depression" doesn't seem like such a crazy thing to need to quantify.

> I tell you I feel good if there's more greenery in the city, you want proof to see "how" good before you build more parks?

A very disingenuous comparison, I think. There's a pretty big difference between that and "What is the effect of certain environmental stimuli during surgery"

I'd really rather not have surgeons explore this question on their own.

I don't disagree that we don't need nearly as much data on some things as others - but I do still want data supporting reasons to spend millions of public dollars.