The extent to which we face equity-efficiency tradeoffs is really overstated. A lot of the time we're sacrificing efficiency to maintain inequality 
Income inequality has a significant negative effect on the long-run level of GDP per capita in developed countries papers.ssrn.com/sol3/papers.cf…
Making wage structures more egalitarian can boost productivity at the same time
(see also: cepii.fr/PDF_PUB/wp/201…)
(see also: cepii.fr/PDF_PUB/wp/201…)
The existence of child poverty is staggeringly inefficient (to say nothing of the moral question). The costs we pay as a society for under-investing in kids far outweigh any costs we'd incur (taxes, incentives, etc) addressing the problem sesp.northwestern.edu/docs/publicati…
Also, *gestures wildly at our entire healthcare system*
Plus, as @mattyglesias points out, inequality has a way of ruining efforts to use efficient market based systems for allocation
I’m reading @M_C_Klein’s Trade Wars are Class Wars right now, and it’s making a pretty compelling case that within-country inequality has also massively distorted the efficiency of international trade
All of this is not to say we’ll never face that tradeoff. It’s just that we’re so far from the point where that becomes a meaningful tension that it makes no sense to worry about it until we’ve dealt with the low hanging fruit
