I would blame that on bad packaging.
My second job while in college was working part-time at UPS as a night shift package handler. My job was to load the package off the conveyor belt onto the 18-wheeler trucks destined to another package handling facility. The boxes are stacked on top of each other and it's sort of like tetris, you find a box that fits into a spot to make a nice stable "wall" in the truck. You build these walls until you get the entire truck full. You are rated by how many packages you can fit into a truck so it wasn't uncommon to throw boxes into the empty areas between the "walls." But another common thing I saw guys do (I didn't do it, I used a step-stool that they instruct you to use but it's heavy and is a pain to move around), and that would involve grabbing a box and stepping onto it to reach the final top levels of each wall. Usually the box would get squashed. This guy that worked the bay next to me (there were about twenty bays at this facility) he would get temper tantrums when the supervisor told him to hurry up and he would throw the packages across the truck or sometimes stomp on them and then he laughed. About 80 percent of the guys working there were complete morons. The conveyor systems can also be a culprit because sometimes the conveyors empty into a moveable carton. The boxes fall down a chute and if a box gets stuck then it will be pounded with something similar to a broom handle. Also, the package handlers hate heavy packages. They are usually susceptible to being "dropped" a couple times.
If you want a package to be "safer", don't ship ground because those packages are most likely to be handled by an *******. Those are low-level packages that get handled by at least a dozen handlers before they get to you. Also shipping during the christmas season is hell at the UPS facilities and that's probably when most package damages occur.
But all of these things can be avoided with proper packaging. It's important to use a good strength cardboard box and then the item should be cushioned.