Many cities across the country subscribe to the concept of "public safety pay parity." From Atlanta to Dallas to New York City and San Francisco (and many cities in between), firefighters have effectively lobbied city and state governments to pay them the same as police officers. But the labor markets for firefighters and police officers are no more alike than the labor markets for engineering professors and history professors. Colleges that would mandate equal pay for history and engineering professors would end up with history professors from top-ranked schools but would have trouble filling the engineering positions. Though both groups are professors, teaching history and teaching engineering attract two very different groups of people with different opportunity costs. Engineers have much better opportunities outside of academia.