You are correct. At most American airports, all you have to do is go through the security gate and pass your luggage through the x-ray scanner. In most cases, this equipment is very poor and misses detection of potential hazards--all the while still inconveniencing innocent travellers.
I was horrified when I found out about the NTSB's findings about airport security and FAA regulations--they sent dozens of undercover agents through security checkpoints at many major U.S. airports. And you know what? More than 30% (I believe this is correct) got through without any problem whatsoever. I have no trouble believing this.
When you consider the ease of smuggling a bomb or gun onto an aircraft, it's downright scary. We always were told that we were safe flying American domestic flights--Pan Am 103 was a result of poor international security. Bull. The FAA has dragged ass on security in this country for years, instituting those pitiful "security questions" that travellers must answer before receiving their boarding pass. Now we see the ramifications of the FAA's failures to ensure the safety of the American travelling public. It's downright disgraceful. And yet again, just like in the ValuJet disaster, the FAA's complacency has cost American blood. For shame.