It should be measured within the geographic bounds of where you can relatively freely and easily move within. If you're making 80k, maybe don't live in San Francisco (or do, but then you need to cut back other expenses).

And yes, I know, it's not easy to move for everyone to another city or region because of several reasons, but generally speaking most Americans could move to another region where they would get a similar paying job and more value for their buck.

Edit: Typos