The greatest risk is from the way that the bags are thrown, rather than placed by the handlers.
As RT says, bags are in containers but watching how they place them into the containers and then out onto the belts is an education.
When going s/h I often watch with fascination as the staff throw bags and drop them, rather than lifting and placing them. They do this when loading s/h right outside the windows and know that their customers are watching them drop and kick the bags. Since they do this where we can see, I can only assume they do worse when we cannot.
Folks think that a tube of cream or plastic bottle of shampoo has burst open in their bags 'due to the altitude', I have always reckoned it is because of the way the bags are thrown and dumped.
I once had to place an external CD-RW drive into a suitcase and wrapped it up as best I could. It works - but makes a grinding noise with each revolution. I would never let a laptop near the hold.