system
Given the following post, respond as if you're commenting on Reddit:
human
Why are wages earned between members of different countries only measured in how much you earn in Dollars/ Pounds/ Euros, while not accounting for the purchasing power in those countries?

This has perplexed me for a while... why do some economists or statisticians compare the salaries of certain fields only in a single currency?

I mean... if you earn $10 000 each year in South Africa, you'll be one of the top 10% of the country's earners... and you can comfortably live off $4000 per year anyway... 

My question is... why compare the earnings in countries when not accounting for the Purchasing Power Parity in each country? One sixpack of beers in SA cost the same as half a beer in Europe, so in beer terms earning half as much in SA makes no difference...
gpt
Well, the answer to that is, you don't, you usually take differences in purchasing power into account, unless it makes sense not to.

Could you provide some examples where you think this has been done wrong?