With more detailed purchase history available it seems like price indexes should switch to purely volume weighted adjusted price indexes. The quantiles of purc

With more detailed purchase history available it seems like price indexes should switch to purely volume weighted adjusted price indexes. The quantiles of purchase history would show a much more accurate history of consumer behavior over time; A rise in the ~10th percentile price of goods by volume is a pretty clear indication of fundamental inflation whereas median or higher percentiles may only reflect fads, substituted goods, or improvements in quality, for example. Maybe such an index already exists? It looks like CPI is switching to this kind of price adjustment for some categories but it seems like the data is readily available for basically all consumer goods; Are stores reluctant to share the volume and price of goods at the individual UPC level?