Don't they realise quite how easy it is to check in a bag for a flight, then not turn up at the gate? Who needs to be suicidal?
Until the USA Government mandates sufficient security procedures to force US Airlines to carry out sensible checks, they are playing russian roulette with the lives of passengers, crews, and (as we have now seen) thousands of people on the ground.
They need to stop their lily-livered kowtowing to business and realise where their duty lies, which is in legislating safety into their procedures.
The blinkered and smugly self-satisfied attitudes of many American airlines was a major contributory factor to the events of the 11th. September.
When people realise that making money is not the be-all and end-all of business, we will start to have a society in which people care about each other.