Because the company chooses to have a policy that mandates employees live within a viable commute radius of an office located in the city. I don't know why companies can't just take responsibility for their decisions.

Or the company can walk down to city hall and tell them to build more housing, because they're unable or unwilling to pay enough for people to live in a viable radius.

Or the company can relocate or establish a satellite office in a lower cost of living area.

Or the company can pay people commensurately with the cost of living in the area.

Or the company can deal with the inevitable attrition of their workforce as it happens, all the while denying that they have any agency and deflect blame onto individuals.