My opinion is based on this generally being a thing that delivery drivers choose to do. It has been true of long-haul truckers for quite some time (many of them would even take Meth just so they could drive longer and log more miles).
This sentence says nothing. How do you know this is something that people choose to do?
https://www.roadsideamerica.com/story/47231
Oh, and here is a literal company that sells a product meant to alleviate the need to urinate in bottles. They speak about such bottle urination near the bottom of the page: