This is a fantastic point.
Apple has several requirements before you can publish an App. One of them is getting a DUNS number for your business.
So why isn’t the government going after Dun & Bradstreet? Shouldn’t they be checking to see if the entity requesting a number is sanctioned?
I’m betting that once a company has a valid DUNS number then Apple goes on to the usual vetting process (like Apps not abiding by App Store rules) and spends less time checking if a company is sanctioned.
Apple needs to double-check companies, but I think D&B bears primarily responsibility for issuing a DUNS to a sanctioned company.