Thank you, dumb me missed it. Their paper talks a lot about measuring poverty. Earlier research showed poverty in China being high in the 80s under socialism and decreasing in the 90s when they became more capitalist. But the formulas for calculating that involved the prices of all consumer goods, including things like airline tickets, cars, big TVs, etc. But If you take these authors' approach and ignore the prices of things poor people never buy, the math shows very low poverty in the 80s going up dramatically in the 90s, because introducing more capitalism brought down the cost of middle-class and luxury goods but increased the cost of rice etc.