Another powerful advantage of dogs is their mere presence at a checkpoint would have a profound deterrent effect. A suicide bomber could swallow a bunch of condoms full of explosives and a small detonator and approach a strip search scanner with absolute confidence his terror mission would be successful. However a terrorist approaching a checkpoint carrying explosives and encountering a dog would have to feel serious doubt about the likelihood of successfully avoiding detection, irregardless of the dogs actual skill level. I suspect he would be many many times less likely to even try that checkpoint in the first place.

IMO the last two bombing attempt failed specifically due to a similar deterrent effect from WTMD's. Both the shoe bomber and the panty bomber failed in their terror missions due to not having a proper detonator for their bombs. The only plausible reason they did not have a proper detonator is, it would contain metallic components and they were not confident it would pass through a WTMD undetected. So they didn't bring a proper detonator and their bombs BOTH failed because of that simple fact. Dogs would present a similar and even more profound deterrent effect. OTOH Strip search scanners and groping don't have the same deterrent effect because they are easily defeated with almost 100% certainty by using tactics to carry things internally.