The only thing I've seen is an option where you can set a budget yourself.
The answer to how it handles the luxury tax as I know it is it's applying it correctly just like real life standards, but there's nothing to detract you from it.
See my OP, I can have $160mil+ payrolls every year, get heavy into the repeater tax with seasons of $400mil in expenses and $100mil losses, and it doesn't matter. I can just keep doing that every year. It's basically just a number, it doesn't force you to do anything.