One caution there; if you read the small print, they're using PPP figures. Which is definitely better than using nominal figures, but doesn't account for anything. In particular, it doesn't account for transfers, either direct (social welfare payments) or indirect (subsidised healthcare, housing, childcare etc etc).

Not to say it's a useless figure, but it can mislead (especially for lower income people, where healthcare costs and childcare costs, say, might be literally 0 in some countries, and a huge part of their income in others).

And obviously for people trying to do the FIRE thing in particular, healthcare costs are likely to be a very big deal; for those in countries like the US where most people get healthcare through their job, that's an additional consideration that people in countries where it's done by income-based subsidised insurance, or free-at-point-of-use systems, don't have.

"In particular, it doesn't account for transfers, either direct (social welfare payments) or indirect (subsidised healthcare, housing, childcare etc etc)."

I believe your claim may be incorrect:

"Depending on the country and year, the data refers either to income (after taxes and benefits) or to consumption, per capita."

I think they are trying to place a dollar value on healthcare and childcare provided by the state and incorporate it as "income". I might be misunderstanding. It seems like a very imperfect science, but about as good of an effort as anyone has made.