As soon as a certificate is printed, an automatic notification is sent to the applicant including when to pick the certificate. Problem is some applicants use middlemen to apply for them, so as a matter of procedure,the notification is sent to the email that applied. And that’s how you might miss it. But we surely do notify.
Your system of police clearance certificate still needs some upgrade, the system should be able to notify the applicant that the certificate is ready for picking. How can someone waste transport to interpol, just to be told it's not yet ready