A window on the 30th floor certainly isn't an escape route but the requirement does still enforce certain standards that in turn promote fire safety. A window means that every bedroom must be on an exterior wall. That simple rule means one cannot build huge warren-like buildings filled with tiny interior apartments, which would be an evacuation nightmare. The rule also forbids bedrooms deep underground.

Yes, this does make apartments more expensive but so does every rule that sets a minimum construction standard.