My experience doesn’t line up with most of what you are asserting.

Many companies do have reasons to want employees in high COL areas, e.g. to be closer to the office, closer to customers, or lower travel costs.

And it is not uncommon to receive COL bumps upward when moving to higher cost locations. It is advisable to do this so that you keep your employees happy and don’t have them jump ship to other employers that will pay more.

It is entirely possible that I worked mostly for unethical companies.