The “standard of living” seems like a straightforward concept: Take some measure of the typical income. Compare it to some index of consumer prices. The resulting ratio should give you a snapshot of society’s level of material well-being.

But since the end of the postwar boom, that snapshot — typically based on measures of private, commercial consumption — has come to seem increasingly misleading.

As technical progress has driven down the prices of manufactured goods, the main burden of working-class household expenses has been shifting to what we might call “mass services” — services that are unavoidably collective in nature. Think health insurance and long-term care. Day care and higher education. Transportation and housing.