real wage stagnation is a social policy, not an emergent phenomenon. Politicians are concerned about unemployment numbers, and there is this bogeyman that "sticky wages" of lower classes gets in the way. The prescribed way around this is to decrease the real value of money and incrementally dislodge the liability of employing lower classes.
Systemic inequality is generated, by deliberate inflationary policy[0], it is not a "universal constant of the universe".
https://krugman.blogs.nytimes.com/2010/02/13/the-case-for-hi...
"Even in the long run, it’s really, really hard to cut nominal wages. Yet when you have very low inflation, getting relative wages right would require that a significant number of workers take wage cuts. So having a somewhat higher inflation rate would lead to lower unemployment, not just temporarily, but on a sustained basis."
[0] I do, for what it's worth, think that liberal economists aren't acting in bad faith, they're just clueless, mostly because if you're a liberal economist (or almost any economist, really) you've probably never been poor.