That toss may be equivalent to what the box experienced during pickup, unloading, sortation at the FedEx hub, shipping, and truck loading for the last mile.
So the FedEx driver sets his "Treatment Meter" according to his "behind-the-scenes" observations.
I've worked in restaurants, and how the food is treated & handled in the kitchen, behind the scenes, is definitely not the same as how the food is treated in the customer-facing part of the restaurant.
I always laugh at jokes like:
"Waiter, there's a fly in my soup!"
Oops, that fly slipped through! Well, there's probably dozens of flies in the kitchen!
And if the fly was scooped out, does that make the soup any safer?
ie: If the box was NOT tossed on the very last leg of its journey to your door, does that mean its journey was more gentle?
Yes, complain, so things might change for the better.
But you probably know the behind-the-scenes journey will still remain brutal....
(I sold sortation equipment to FedEx, USPS and UPS. I saw the Behind-the-Scenes situations....