What Jake says is, of course, perfectly possible.
However, as far as I know, Muslim extremists have not yet managed to persuade any 80 year old English grannies, or any 30 year old Christian parents travelling with their children, or indeed any white people with a proclivity for dressing as a Boy Scout, to secrete explosives about their person before boarding an aircraft.
Up to now all recent terrorist activity connected with aircraft has been confined to young dark-skinned Muslim men. Until this is shown to be otherwise there really is no point rummaging through the knitting bags of 80 year old grannies, or ripping the limbs off children’s teddy bears. I know you cannot identify Muslims by sight, but you can identify young dark skinned men by sight. The government (which sets the policies) should allow the airport authorities to exercise its discretion and target their limited resources by using some intelligence.
Unfortunately its approach (as with many things) is to identify all travellers as potential terrorists and considerable resources are wasted screening people who pose no threat.
If profiling at airports is in place as sp suggests it clearly is not very sophisticated. It is obvious that to single out only young dark skinned men would offend the usual liberal lobbies and so cannot be permitted.
Finally, to confuse this issue with the prevention of drug smuggling is disingenuous. The two problems are completely different and they cannot both be solved by a single solution.