That depends on which branch of FedEx you are talking about. FedEx Home Delivery (purple/green) is (or was) contract drivers, FedEx Express (Purple/Grey) is not (or was not) contract drivers. They worked for the company and didn't own or lease their trucks that they drove.
If they are overcharging you for weight, or for measurement, call them to task on it at that time that they fill out the bill. If you weigh the box on your scale, and they weigh the box on their scale, and both are certified, then somebody's scale is wrong...... I believe that if a box weighs 5 pounds one ounce, then you are charged for 6 pounds, not 5. Think of the bill as a contract between two parties. If you agree to it, you sign it and pay the amount. If it's disputed, the dispute needs to be ironed out before the contract is paid.
Or, just do like a lot of businesses are doing. The buyer pays for the shipping charges, and they get to pick what service they want to pay for. If FedEx is a PITA to ship from, then don't offer that as an option.
i.e. for me here, UPS has better delivery service and better customer service than FedEx Express, FedEx Home Delivery and USPS both run about even in regards to timely delivery and customer service. UPS will put a package inside my enclosed back porch, out of the elements, rain or shine. FedEx Express will put it inside a clear plastic bag and put it out in the weather by the front door if it's raining, no bag if it's sunny out. FedEx Home Delivery will leave the package by the front door, no bag even in rain/snow and USPS will leave the package in the driveway at the base of the 2 step concrete front porch or put it by the front door, no plastic bag, no matter what the weather is.
(The door to the back porch is literally less than 25' away from the front door.)
