on security checkpoints

Be it in malls, the MRT, or any establishments, I still can't dig the purpose of the security checkpoints. The security guards are being paid for merely opening the bags of the masses and making dutdot the stuff inside the back with their magical wands ala harry potter -- "wingardium leviosa". As if they are actually checking the items inside the bags. Restricted items won't float and reveal themselves just by poking random items inside the bag with the stick.
Kakainis.

Photo credit: http://www.life.com/image/1537501