I believe the use of metal detectors has made us safer. To me, metal detectors are normally not invasive and their use generally means that firearms and weapons won't make it past the security check point. I think without these devices weapons would be more common in places like schools, courts, and airports.
We are safer as a result of using body scanners. This is because of the fact that scanners can find dangerous things on a person. Without scanners we wouldn't have the extra safety involved when people pass through things such as customs. Someone could easily bring something dangerous through if they weren't scanned.
Body scanners can be a good thing if they do not show people being naked and are not used in the back rooms as places to invade the privacy of travelers. But right now that is what seems to be happening and it does not seem as if they are better than other means of checking passsengers.
No, we are not safer as a result of using body scanners, because the body scanners have a lot of flaws. Studies have been done that show that the scanners do not always catch everything, including serious weapons. But the body scanner does work well enough to allow a TSA officer to pat me down when I forget to take a hair tie out of my pocket. It is just a ruse.
Body scanners haven't led to a major increase in security, and they've actually led to a major invasion of privacy. We aren't safer as a result of airports using these machines. In fact, our rights have been further eroded with the introduction of these devices, and they need to be eliminated.