Screening at airports can be broken down into what items are to be detected.

Guns, knives and such are detected by WTMD and HHMD.

Explosive components can be detected by explosive swabs and ETP, although TSA tossed their ETP equipment in the trash.

WBI machines rely on the operator evaluation of the image to function and it is proven in other Red Team testing that TSA operators can not be relied to detect targets on other equipment that requires a human evaluator.

If TSA can detect explosive components, ETD & ETP, and detect metallic weapons, guns and knives, just what else do they need to interdict?

Both of these can be done without violating a persons privacy or dignity.