Proof that money does in fact buy happiness

One of the biggest problems with Deaton & Kahneman's "happiness doesn't increase after $75k" is that cost of living is very different from place-to-place. At least this article points it out.

In the best version I can find (anyone have a link to the original paper?), they don't address this in their study. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&...

Money doesn't buy happiness. But it has a role.