[ghaff]

Costs differ by location. Formal per diems, even with some attempt to adjust, end up screwing employees who are in higher cost locations (and/or have higher standards). Which may be fine--or not.

But, to the degree that fraud becomes a real issue, it may be the simplest thing to do.

[maxerickson]

Shorting someone who is getting funds for lunch by a couple bucks is not in fact "screwing them".

[ghaff]

Perhaps. But I also have standards for both accommodations and meals that I never pushed too hard on but may be different from those you have. If work travel is consistently costing me a lot of money, I'm going to have an issue.