Fifteen seconds on Google turned up an unofficial forum for UPS workers. Pissing in bottles appears to be extremely common. From perusing a few threads on the topic, the zeitgeist appeared to be "everyone does it, but if you leave your piss bottles in the truck after your shift then you're an asshole".
https://www.browncafe.com/community/threads/what-do-you-do-w...
https://www.browncafe.com/community/threads/urine-bottles-in...
https://www.browncafe.com/community/threads/urine-bottles-le...
https://www.browncafe.com/community/threads/urine-bottles.36...
It is also possible people actually prefer to do this rather than stopping frequently and dealing with the hassle of finding a place, parking, running the risk of it being a single restroom and already being occupied.
[0] https://www.browncafe.com/community/threads/what-do-you-do-w...
What? Those are two distinct and not comparable things. Besides, being a driver can be pretty hefty labour and you'd be stupid not to be drinking lots of water while you work.
And of course they're not pissing in bottles every day. The problem is that they don't have the time to take a rest break due to the unrealistic volumes of deliveries each driver is expected to make regardless of traffic, weather, or other conditions.
Want to emphasize how bad workers have it? Just tell people they’re pissing in bottles!
The reality is no, workers aren’t pissing in bottles. At least not on a regular basis anyway, and not because they were forced. If they were, it means they’ve been drinking tons of water. But how would they have time to drink so much water if they supposedly don’t even have time to take a bathroom break?
Awareness of your own bodily functions is just a part of life. One that people take for granted, until it puts them in a difficult situation. There was once a time on my way to work I got stuck in a bad traffic jam and had to shit really bad. Eventually, there was a point where I realized I wasn’t going to make it and started rummaging through the backseat for any kind of bag.