I don’t exactly know how to describe this, so…
Basically, you can set all salaries to -100%, effectively turning all your staff (Except Board-Members) into volunteers. I suppose that, later on, staff-mood will be added to counter this, but for now, you can just get away with never paying your staff a dime.
But doesn’t that decrease your Airport approval rating.
AFAIK there’s a notice-able performance difference for your staffs, but it’s not much.
Interestingly, IIRC there’s a bug that means if you set the salaries to negatives, you’ll be “losing money” in the screen but in reality those reds turn into green into your account and you gain money from all your expenses and income.
Walmart Airport.
I’m currently running an airport with -100% salary, and 98% Approval, so I doubt it. It isn’t much atleast!