The pentagon spent 19 billion to determine that the best way to find bombs is with a dog?

Dogs are effective but must be rested, they don't work 8 hour shifts so you are going to have to have quite a few packs of dogs at each checkpoint, that equals a lot of dogs. Now you have to feed them, walk them, house them, etc... So we'll hire some more federal workers to do all that. Meanwhile, people are scared of dogs, people are allergic to dogs, people may not like dogs getting all up on them sniffing them, some cultures consider dogs unclean, it's a whole different can of worms.