Easy. You hire more low skilled workers and run them in shifts because warm bodies are abundant and overtime is expensive. High skilled workers have a high fix

Easy. You hire more low skilled workers and run them in shifts because warm bodies are abundant and overtime is expensive. High skilled workers have a high fixed cost per employee, low to zero marginal cost per hour. More hours from fewer employees is an obvious strategy to deliver the growth shareholders demand. By convention and legislation, high skill jobs pay invariant of hours worked and are overtime-exempt. Low skilled jobs can be filled with whomever happens to be born nearby, so they can be distributed across small towns. High skilled jobs require the best people regardless of birthplace, and both employers and employees are incentivized to seek a large pool of potential counterparties to optimize wages and "fit." This naturally creates "destination" cities where inward migration of highly paid workers raises prices and therefore COL. Stagnant wages - because labor intensive businesses aren't good enough investments anymore to have lots of employers bidding up the price of labor (except in some niches).