why didn't lifelock catch a credit card application

I received a credit card in the mail today that I did not apply for.  I have called the cc company and cancelled the card and they reported it as fraud.  I will also be filing a police report.  My question is why didn't life lock catch a credit card being open in my name.  I have been on the phone with life lock for 40 minutes and have gotten nowhere with this question.  we have gone around in circles.  Not sure why I am paying for a service that didn't catch a credit application.