The event looked a bit off to me though, the text made it appear as if they still had to be paid, but in fact they were autopaid like they were supposed to.
Describing military npc's as workers in the event looks a bit odd as well. If we dont wanna name them NPC in the event then maybe "employees" or "personnel" looks more fitting.
The formula for the wages they have to be paid is:
hiring cost * (0.15 + (0.01* xp level))
So that would be 16% to 18% of their hiring cost.
Not even the sky is the limit !