One reason might be the PC problem where we have to profile the same number of grannies with knitting needles as the ragheads to keep from being accused of racial profiling. Also, it seems the Israelis have a handle on the borders and the people who might cross them.
I think it has a lot to do with not being sued. CAIR and other islamicist groups have armies of lawyers waiting to sue the government. El Al has never had a hijacking btw.