The worker cannot easily compare compensation offered by different employers, so they are less likely to leave. And bigger/more profitable businesses can afford to hire professionals to analyze and implement these benefit plans, while small businesses are left competing for 2nd tier employees since they cannot afford that overhead.

Why someone gets health insurance and retirement savings with pre tax money if their employer subsidizes it and why someone has to pay for health insurance and retirement savings with post tax money if their employer does not subsidize it is a pretty great injustice that neither party is interested in addressing.