Okay carry such thinking to its logical conclusion -- no one should be able to enter the Beltway without crossing a one-mile wide free-fire border zone naked. No vehicles except those fully searched by complete disassembly and re-assembly and microscopically examined. Afterall someone could backpack in a nuke, literally, in a backpack on their back. Or some A-cup woman could have a D-cup bra full of anthrax. Or some dirty bomb bolted onto a Mac Truck transmission.
Most any aircraft will take off with significantly more than the legal gross weight if the air is cool and/or a headwind at takeoff roll exists and/or the runway is long. The key is keeping the CG at close to the right place. No terrorist is going to be concerned with FAA legal gross. Alaska bush planes get away with outrageous loads at times.