Why dont package delivery(UPS, FedEx etc.,) vehicles have doors?

Question

Why dont package delivery(UPS, FedEx etc.,) vehicles have doors?

Answer 1

The obvious...

The drivers are constantly getting in and out of their vehicles. So why have doors on them?

Answer 2

Think about it. If the driver had to open and close a door every time they delivered a package, they would slow up their service time. It must be terrible in the winter.

Answer 3

They have doors, but are left mostly open.

Answer 4

I cant believe how many people think that our trucks dont have doors!!! You can see the handle right there. They just slide open and latch that way. Its MUCH  cooler with the doors open.