I don't think most have a problem with employees taking seats when they are traveling to or from work. Traveling to work because they need to get there for the flight to fly, and traveling from since they're tired and wanted to get home just like the rest of this. And I have no problem with employees in First Class after all other waitlisted customers have been processed and served.

But the problem is, of course, when an employee not travel to or from work takes a seat in leiu of a paying customer, since the gate agent is their "friend" by definition (fellow employees=friends, while passengers=enemy).