I think it's probably a lot easier to break down your income into budgeting categories when you're making a little more. When you're taking home less than 30k, it doesn't really matter what the money is called. Per diem, income, whatever. It's all critical. Every dollar is a dollar closer to your rent payment.

My old boss in a previous career had a "car and driver" category on his paystub...this guy made maybe 8 million / year, and had a "car and driver" type of per diem worth $14k. Made absolutely no sense.

The greater point being - doesn't matter how the company breaks it down. It's all money that you decide how to spend.