Often, licence agreements stipulate that they are not transferable and thus you have contractually agreed not to resell them. To what extent this is enforceable is… contentious. Different courts have struggled with the topic and have ruled both directions on the issue.

Copyright law as written was not designed for immaterial goods in any way, and the DMCA has done little to improve that. So effectively the judicial branch is in limbo. Corporate America is content to leave the confusion as is. They can just adopt an interpretation of the law that is maximally beneficial to them, and consumers generally don’t have the resources to challenge that interpretation.