I used to drive an old 8 wheeler skip lorry which ocassionally used to snap a stud on one of the drive axles , initially It was blamed on me hitting the side of the weigh bridge where I was tipping 
but I pointed out that wasn’t possible as it was only 6" high side to the weighbridge .
In the end it was blamed on a faulty batch of studs as it happened a few times .
I fail to see how loosing one nut or stud would require a new hub ■■
I don’t see how they can take the cost off you unless it’s in your contract but then again many employers seem to think they can do what they like …