I wonder how expensive that raincoat was that the person thought it needed to be its own line item on the expense. That's normally what the incidental expenses line is for, so this is just a story of someone who filled out his expense report incorrectly, got it rejected, and then filled it out correctly.
A good raincoat is pretty expensive. At least $200. So the guy submits an expense report with a $200 line item, gets rejected and splits the $200 into probably 7 or 8 incidentals which usually have a $25 limit, probably on different expense reports.
I'd take a double take at a $200 line item for an emergency raincoat to replace one that I lost on a trip. I'm not asking the guy to get a plastic poncho for his business meeting, but he doesn't need to get it at the Gucchi store.
Reminds me of a time I worked in a company that reimbursed us for coffee expenses on business travels. In their system, I had to itemize every receipt, so my expense report ended up being 50% made of morning espressos. The secretary handling expenses came back to me pretty annoyed and told me that next time, I should buy a pre-paid Starbucks card instead.