For sure there's lots of security at Disney. Some of it is unseen and it's no doubt layered. But I think some people tend to overestimate how extensive it is.
How about cameras? There are lots of them for sure, but I'd bet that 95% of them are passive, i.e. they're recording for future examination in the event of an accident, injury or crime. Active monitoring has been studied extensively and it's hugely ineffective and inefficient. The human attention span starts wandering after only 20 minutes or so. Monitoring 4 parks, 2 water parks and Disney Springs would require hundreds if not thousands of cameras. Not to mention you'd need many hundreds or thousands of CMs and acres and acres of office space to accomplish this. If that infrastructure existed, we would know about it.
Facial recognition software? What database are the faces being run through? CIA, NSA, FBI? That would probably amount to a long list of felonies for a long list of people. And if I wore a ball cap, sunglasses and didn't look up - no picture.
Hidden magnetometers? To what end? What happens when someone with intent to do harm rolls in on an ECV with bad stuff hidden on board? I know a guy (not law enforcement) who always carries - everywhere, including WDW. And that's 5 or 6 dozen times every year. He's never been detected.
I happen to think Disney security is pretty good, and I'm glad it's there. But if it were as pervasive as advertised, then you wouldn't have people climbing pyramids and not getting caught. And you wouldn't have people filming commercial movies and not getting caught.