Hmm. I did not know that the commercial carriers (UPS, FedEx, etc.) are not allowed to back up. I do remember many, many years ago, those USPS Jeeps were not allowed to make a left turn. Ever. Statistics showed that left turns caused more accidents than going straight or turning right.
One time I talked to a Flex driver right after he dropped off my package. He says it's a good gig and pays well. Most delivery blocks are 4 hours long and that's what they get paid for, even if occasionally they can get it all done in 2.5 hours. But it can also go long and they work more than 4 hours. Usually they have to deliver 40-60 packages per 4 hour block. I noticed that this Flex driver had an Uber sticker and a Lyft sticker on his car too. I joked with him that he must love driving to do all three. He seemed like a nice guy and probably more professional than many of the other Flex drivers.
All these driving jobs boast $15 or $20 per hour. There are some websites that do the math and calculate the actual pay rate. One site I read compared Uber to a pay day loan. That is you get money right away (or almost right away) but you have to pay back more money in the future in gas, insurance, repairs, maintenance, wear and tear, resale value, income tax, etc. The site estimates that the actual net pay rate is somewhere between $5/hour and a negative value.