I spend thousands of dollars of other people's money all the time. I get receipts. It's a simple way to never have these problems, for my clients to know I never stole their money.
I've never faced this kind of refusal to document expenditures of other people's money without there having been fraud. People that didn't steal showed proof they didn't steal. People that weasel around it, deny there's any reason to suspect them of theft, well, they're always thieves.