Sure, totally make sense, but also keep in mind a few things.
even that the demand for burgers is somewhat the same wherever you go
Actually, it’s not quite right, because the demand is different in some countries and the “status” of burgers is not the same either. Some poor countries still have Big Mac’s only in big cities. For example, in poor South East Asian countries burger is kind of “entertainment/luxury” food, so the price is much higher, than for a full meal of some common street food.
My comparison method would be to start by turning a gross salary into its local net equivalent, apply the purchasing power ratio and turn it back to gross with the target tax rate.
Yes, sounds reasonable, but here is a tricky thing about taxes.
From one side, US and Canadian citizens pay really high taxes, so they can keep less real cash from their salaries, but at the same time people get really high retirements, good firefighting services, police protection, amazing roads, unemployment benefits and so on.
In Russia people pay less taxes, so they have more cash from salaries, but at the same time people get very small retirements or social benefits, roads are horrible and so on. By the way, Russian medical care is free, even though it’s not the best quality.
In some Asian countries people pay very small taxes, so they can keep lots of cash from their salaries. But keep in mind that there are no retirements or social benefits at all, and people need to pay money every time they call to a police, even if there was a crime. And people need to bride police and other authorities on regular day-to-day base, because the police is very corrupted, because they have very low official salaries, because the government budget is very small, because nobody pay taxes.
So it’s really hard to compare developer’s salaries across the countries.