Airport Security?

I'm trying to figure out how airport security works and here's my theory: People are scared to fly because they think terrorists are going to hijack the plane. The airlines step up security to "make things safer," but are so afraid of being sued or are trying to be politically correct that they wrecklessly endanger millions of people because they have to pretend we're all equally likely to be terrorists. Hmmm, let's see, the airlines can't possibly check every single person and bag (thoroughly) before each flight, so they "randomly" check certain passengers. Since they can only check a percentage of passengers, you'd think they'd maximize their opportunity and check the most-likely candidates for terror, not unlike smokers paying more for life insurance - statistically more likely to have heart disease, high blood pressure, etc = more risk. Yet the airlines don't do this. Young, single, Muslims of middle-eastern origin are about 1000 times more likely to be terrorists than 80-year-old men, middle-aged women, children, and me - born in Pennsylvania, married, pushing 40 and as white as can be, yet I get searched EVERY SINGLE TIME I fly because I have a "common" name. Last time I checked, there weren't any Al Qaeda bad guys named Smith.