Having worked at 680News not that long ago, I can tell you that the way they make money is by having very few staff on hand. Jack FM is pretty much totally automated most of the day, and CHFI is pretty much the same thing. Most times I walked by those stations, the lights were off, save for the glow of the automation computer monitor.
On the AM side, 680News is staffed by a bunch of people during the day, but is pretty much a ghost town overnights and on the weekends. Five people keep it on the air most times. Overnights it's down to three.
The FAN uses many, many unpaid interns that monitor game feeds and dump highlights into the audio playback system.
Expenses are low, staffing is lean, and ads pay the bills.