Well, here is the way it was explained to me when I first started working out of town in the 80s. Per diem for meals is to help offset the cost of eating in restaurants as opposed to eating in your own home. You don't expect your employer to pay for your meals when you are home. Why should they pay 100% for nice restaurant meals every day out of town when that is something you might only occasionally splurge on when you are home? It made perfect sense to me then, and still does to this day. $20-25 per day even today in almost any city is more than fair, and if you want to splurge, pay for it yourself.