Sure but, at least compared to when I was a kid, it is a lot harder for people that don't belong there to get on bases now. Both this guy and the last Ft. Hood shooter weren't going to be kept off base because they were supposed to be on base.
Depends on the base, not all of them actually scan the cac. Yokosuka does, Norfolk Naval doesnt, and the majority of my training bases didnt. Quick flip and carry on.