poisson,
Drug smugglers, not so much. But the initial questions and document check are designed to identify those who may be refused entry into the United States. The airlines face large fines and logistical challenges with those situations. So the interview and document check verify that a passenger has appropriate visas, etc., isn't on a "no fly" list, and then the questions are in the interest of security.
I find the questions to be useless but generally unobtrusive. It's just so silly to go through it twice, but this practice long predates September 11.
They used to make a bigger fuss of appearing to work for the airline. They would say, "I work for American Airlines Security" and would wear the uniforms of the U.S. carrier. Now they tend to wear the uniforms if their real employers and don't pretend to be airline employees. But perhaps it's the old style in Athens.
It would make more sense to pool resources and have all of the U.S. carriers use the same contractor, but then money gets involved. And they would lose their branding. The podiums are "branded" with airline logos and sometimes their premium cabin brand names.