The Teamster union at UPS is just posturing on its demands in the upcoming contract, but usually ends up giving in to mostly what the company offers.
Working in and driving the package cars, the medium size brown vans, is tough, hot in summer, cod in winter and jumping in and out is hard on knees and hips. They have to carry up to 80 pounds and that is hard on your back. All the trucks have GPS and the supervisor calls if you take too long to take a dump or the truck isn’t moving. If you have an accident that’s your fault, you may get fired.
I will say those UPS boys and girls are in shape.
But like you said, my current delivery guy in his 50s is physically out of gas and his knees are bad.