End-user certificates, and the end-use statements that accompany licence applications, are the point at which the export control system depends on a representation rather than on an observation. The exporter cannot follow the item to its destination; the certificate stands in for that.
That makes the certificate the natural target. Published enforcement records describe certificates issued by companies that do not exist, by real companies whose letterhead was copied, and by real companies that knowingly signed for goods they never intended to keep. Verification of the end user, rather than receipt of the certificate, is what separates a genuine check from a filed piece of paper.