There are numerous laws on the books that do absolutely nothing. For instance, it has been illegal since 1986 to manufacture a handgun containing less than four ounces of metal. No such practical design existed at the time, nor was any being developed, nor was there any plan from any manufacturer about ever making one.
I'd imagine this was to combat making guns readily available that would bypass metal detectors. Just because there weren't any planed at the time, forsight may have been enough to avoid that situation? /speculation
