Mitch Hedberg is great, but I've expensed Dunkin Donuts while traveling for work many-a-time. And HR/Accounts Payable definitely want to see a receipt... even for a donut.
My accountant gets upset if I don't expense stuff like that. If you go on a business trip and don't buy the kinds of stuff the government expects you to buy, then they start to question whether or not you actually went on the business trip. It's not so difficult to book a room somewhere and then change the booking or get a refund. But if you are saying that you went to SomeCity and you buy Dunkin Doughnuts in SomeCity, it keeps the auditors happy. I'm always getting in trouble for that (especially for things like local train tickets, bus tickets, etc, etc).
In an isolated instance, sure. But for those who live on the road, 5 bucks a day (minimum) would add up quickly enough. Those people are usually going to be doing the paperwork for other expenses anyway, so just tag it on.
Prefer a per diem rule. This can be a problem if you're my friend who services CT scanners around the globe because cost of living varies so much (the same price of overnight stay in two cities is the difference between a nightmare hostel and 5 star luxury) but if you mostly do the same trips especially in country a rule that says here's say $20 per day for food is easier than collecting and uploading receipts for every burger and coke.
It's easier for you, and instead of fighting expenses abuse and having a bunch of workers to check the expenses paperwork the business just has an understandable cost when it sends people to do their jobs.
