anchoring and information asymmetries (+ information hiding). they're everywhere and especially all over labor markets. where there is information, it's thinly dispersed and often of dubious quality. anchoring is an easy heuristic to fall back on in those kinds of situations (on both sides).

plus, margin contribution is basically impossible to determine on an individual level, and wages therefore devolve into fundamentally political arguments (as in, expressions of power and influence).

you're expecting a (more) rational market response, when the labor market is anything but fair, free, and transparent, and coerced into that form over centuries by those in power.