Hey poppyseed, you are not getting your information from the real world. I can tell you first hand many places have video tape that recycles after 30 days. Some insurance companies give a premium break for this.
I didn't claim to be an authority - hence my phrasing the assumption as a question. But 30 day archives or no, the guy still has to be on-camera at some point, and if he's scouting spots from where he'll be shooting, he'll be out of range of the cameras. Well, that's my guess - which is just that, and no more or less outlandish than some of the other theories we've cooked up on here.
Or maybe he's on gas station cameras the region over. It'd be laborious to cull through them all, but hey, if that's what it takes to catch him, then do it. I'm not saying I don't want to consider the possibility of him being caught on tape - it would be quite a boon if he was - merely that I seriously doubt that he's on all these tapes regardless of how long they run, or even if he is, that authorities are expending the resources it would take to go through them all. At this point, anyway.