I think that factoid comes from that shitty graph where the suppose that the UPS driver starts working straight at the moment they turn 18 and they will have maximum pay rate that is available for the UPS driver position.

While in reality, the average wait time to become a driver from loading is 11 years. During that time you make about $13/hr part time where the schedule can be horrible and you could work less than 15 hours a week. When you do become a driver it takes another ~2 years (on avg) to get your own route until then you are a part time worker and your hours worked will fluctuate a lot over the year. The first year is paid at 17.50-18.50/hr (~$36,000/yr @ 40 hours a week) and then goes up.