The article does take purchasing power into account for geographical differences, and inflation into account for temporal differences. All prices are normalised

The article does take purchasing power into account for geographical differences, and inflation into account for temporal differences. All prices are normalised into an International Dollar across space and time, so that $30 in Cape Town in 1970 would still buy you $30 worth of goods in the USA in 2023. It's outlined in the section[1] below the first graph, and the rationale for those methodologies is also outlined in that section. https://ourworldindata.org/extreme-poverty-in-brief#differences-in-purchasing-power-and-inflation-are-taken-into-account https://ourworldindata.org/extreme-poverty-in-brief#differen...