Yes, but you can't have everything. Apple for sure could have pumped the security and made the chances of a false positive higher, but what good would that have been!? Then the user experience would be really bad.
Im not saying it isn't good enough, I just want to squash the myth that the phone contains some magic making it better at ruling out others when it is actually trying get better at finding "you" in faces "obscured" by makeup/hair/what-ever.