Originally Posted by ivyspice
if someone finds a lost certificate and uses it when they would otherwise throw it away, then United is out $600 that it wouldn't be out if it restricted use to authorized passengers.
And if it hadn't been lost, and the original assignee used it, United is still out $600. Either way, United is out $600. It's actually in their best interest that you lose the cert and nobody uses it at all!
Also, as the certificate is fully transferable, United has no way of knowing if the user received the certificate legitimately or not.