If you finish early, get perfect customer feedback, have no driving infractions, and didn't have to receive any help on your route, and finish an anticipated 40hrs of work in 30, you get a bonus for the week.
Cons
It's usually very unlikely that you'll get said bonus, the turnover is extremely high, pressure to perform makes the average person want to pull their hair out, and on a GOOD day, you'll get a 5 minute break to grab food from a gas station and get back on the road. I've lost 30 lbs in 2 months time, and I didn't really have lots of extra weight.