Comment Common Practice in the Transportation Industry (Score 5, Insightful) 101
Having worked for several delivery companies before, I can tell you this was common practice for me and nobody even asked me to do it.
When you're on the road, and aren't being paid by the hour, it simply makes sense to drink as little liquids as needed and pee in a bottle when needed. Get the job done quickly and get home. I can imagine it's a bit larger hassle for women, but for men it's a trivial issue.