How infrastructure reliability as an intervening variable can recast the trade-off between equality and efficiency

I

A good deal has been written arguing that economic efficiency and equality in economic well-being can move in the same direction (e.g., healthier people are more economically productive). The dominant view, however, remains the two are in The Big Tradeoff: more equality means less efficiency.

All this is curious from the perspective of the social sciences: Why would anyone take a movement in efficiency (or equality) to be caused by a movement in the other rather than caused by some intervening variable affecting both efficiency and equality independently?

II

More institutionally-informed economists say they do talk about intervening variables, at least in the form of secure property rights that underpin gains in economic efficiency. Yet those are no more second-order considerations. For when economists talk about the necessity of “secure property rights,” they rarely see any need to underscore a hugely reliable contract law, insurance and title registration infrastructure in place and “always on.”

Could it be, for example, that consumption is less unequally distributed than income precisely because critical infrastructures have been more reliable in the delivery and distribution of goods and services than they have been in the creation and generation of income opportunities for those doing the consuming?