The answer to your question..."when you started at UPS, you did know the drivers worked lots of hours and late nights, right? is "yes they did". Drivers in our centers (for the most part) are now working fewer hours than they ever have with this relatively new "9.5 initiative" in place. Some drivers thrive and want OT...
FWIW.....my son is a resident physician that often works 12 hour days with 24 hour shifts expected at least 4 days per month. His yearly salary is significantly less than a full time driver and has about $190K in medical school loan debt. Patients can and do spit, kick, bite, punch, etc.. Healthcare benefits are less than what we have under TeamCare. I only mention this in case some of your drivers want to quit driving and are considering a medical career.
UPS jobs in general are some of the best in the world. There is not a part-time job that exists anywhere that pays what I make in addition to the 7 weeks paid vacation and more than excellent health care benefits I receive through TeamCare. While I can and do criticize my Union and UPS at times....... I still appreciate them both and would not have it any other way or work for any other company. UPS has been good to both my family and I over the past 40 years.