The downside is that the system is time consuming. For about 90 percent of the people screened, it takes less than a minute. But for one or two percent, it can take an hour. The rest fall in between those two extremes. Airlines dont like to delay passengers this long. The Israeli method is also labor intensive, and the labor is expensive. The preferred screeners are above-average college grads, who have to successfully complete a nine week training course. Even then, the Israeli find that most screeners only last three to five years, because of the grueling demands of the work. Since September 11, 2001, many more nations have adopted the Israeli system, but few have applied it as widely as the Israelis. The system does work, with many terrorists, or criminals up to no good, getting nabbed.
Other nations are, reluctantly, adopting the Israeli screening methods at airports, and other places where you want to keep terrorists out. The Israeli system, called observation and questioning, has a near perfect record in keeping Israeli commercial aircraft free from terrorist attack. The system is based on the principal that anyone up to no-good will act differently than innocent people. Screeners are taught the tell-tale signs to look for, and the types of questions that will elicit a response that confirms the assessment.