PPP suffers from the same problem that "basket of goods" CPI suffers from in that it doesn't account for differences in quality:
- of course a car costs more today than it did in 1980, it's a far better car
- of course a loaf of bread costs more in California than it does in India - I have certain guarantees about the pesticide levels in the wheat, the accuracy of the labeling, and my ability to seek damages from the legal system in case I chip my tooth on a stone, that I don't have in India
At best, PPP tells you something about the differences in cost of labor. But labor isn't everything you buy.