I happen to believe this is true which makes UPS' business practices that much more mind-boggling. Just for a quick example the cutting of a route. It would make sense if you could just lay the driver off for the day but the contract states you have to find him 8 hours of work somewhere if he was told to report. So now he has to work in the hub making $31/hour for a job that pays $8.50/hour.
This example is very different in other parts of the country. I've seen many centers where the routes are cut and you have 4 or 5 drivers volunteering to take the day off. Generally, the senior driver who wants the day off, gets it. So it's not "laying off anyone for just a day". Some centers always have extra drivers 3 days a week ( with the full staffing in place on the 2 heaviest days), and never have drivers bumping into inside operations (unless a driver is laid off for the entire week).
It's very interesting that this is the same business- picking up and delivering packages, but it's run differently in different parts of the country.