Airport security

I understand the need for airport security, but I often wonder if the measures adopted are too mechanical and  impractical.

Often, the sensors are set at such a low level that it beeps when you pass through the detection gate. Even a  small coin will trigger the beep.

It is quite inconvenient and troublesome to remove the belt, pen, coins, wallet, mobile phone, watch and other items and still get "beeped". One might as well go through the body search, without removing these items.

I know of many airports where the security is more relaxed. They did not get any bombs blew up in the plane.

In risk management, one has to measure the cost and benefits of any risk measure. Is this a case where the cost now outweighs the benefits?