Because the labor market isn't perfectly liquid. Let's say a manager randomly decides that he's firing all the blond haired people in his company. Those peopl

Because the labor market isn't perfectly liquid. Let's say a manager randomly decides that he's firing all the blond haired people in his company. Those people will be harmed. Even if perfectly competent at their jobs, they very well may not find another job right away. It may even be the case that an equivalent job doesn't exist nearby and the employee is SOL if forced to quit without planning. Furthermore, once the company fires all the blonde haired people and this becomes known, there will be cases where competing jobs can now offer less pay because it knows a competitor is no longer willing to hire blond haired people. Now, you might say "the company that fires all the blond haired people will eventually die at the hands of a company that gains an advantage by accepting blond haired people." True, but it's a slow bleed, and that certainly doesn't help the blond haired people who were arbitrarily fired. In case you're skeptical, all this and more can be observed in the case of US black people up until the civil rights era.