Other than the fact the seller may be scanning used or out dated material and putting it on a flash drive and selling multiple copies, what is the harm? Copyright protection? Who cares?
That is sarcasm if anyone missed it. I would hope someone at AWS is keeping an eye on things like this.
There's nothing wrong with selling one's used course materials, but scanning the copyrighted materials and selling multiple copies must qualify as copyright infringement.
There is an outside chance the course materials are from a source other than AWS. I guess we'll never know.
Al