In my apartment building all of the external access doors are held closed by electromagnetic "locks" that require a key fob to open, unless we lose power, in which case there's no battery backup and they're all unlocked.

Jesus, what if that failed in a fire?

In the case of a fire tenents try to get out of the house and usually there is a normal manual turn lock on the inside of the door that works without electricity.

For the fire fighters, I assume they break down the door anyways?

Nearly all smart locks can be mechanically unlocked from the inside (as required by fire safety regulations).