Yes: having CoL-adjusted salaries. Maybe you left this as the obvious answer, knowing that the people who frequent this board would downvote it.
Subsidizing high-CoL people who get the advantages of being in a city is not fair at all. It’s only tolerated because high-CoL cities tend to be where the talent is most concentrated so you have to compete for them.
For example, Google will not pay Zurich engineers Bay Area equivalent salaries despite there being similar CoLs.
Would you think it’s fair if you lived in the same city but your company paid more money to people with more expensive houses?