Somehow, in the middle of a war zone, U.S. forces manage to implement a quick and portable biometric scanning system (http://www.usatoday.com/news/world/iraq/2007-07-12-iraq-database_N.htm).

It works in the war zone because the much smaller number users of the system have their biometric data collected beforehand. It would work at airports, too, if you first took the step of creating a biometric database on everyone in the US. Good luck with that project. And it wouldn't work nearly as well because an algorithm distinguishing between 300 million people is much more prone to failure than distinguishing between 1500 people at an embassy.

From that USA today article about how it's being implemented:

In several neighborhoods in and around Baghdad, troops have gone door to door collecting [eye scans]

I live in one of the most rednecky areas of florida, and let me tell you, government agents driving around here trying to take eye scans of citizens would be met with, shall we say, a very...energetic...response.

Face scanning and comparing to a photo can't work, because the number of false positives is guaranteed to be much higher than the number of actual threats. For as scared as we are, the number of terrorists trying to hijack planes is essentially zero. If you're the TSA employee, and in your 3 years on the job the red flag has gone up 14,789 times, and it's been not a terrorist 14,789 times, do you even blink when the red flag goes up ten minutes from now? Anyway, we're spending way too much money on airplane security compared to other potential threats.

Heck, even at Disney World, they use thumbprints to validate their tickets.

I haven't been to Disney World in decades, so i'm not sure what they're doing, but I'll presume that they're taking a fingerprint one day, matching it with the ticket, and comparing it with the fingerprint of the person using the ticket the next day, so that, say, people don't buy multi-day tickets, go once, and resell the ticket. This is an easy way of making sure person A on monday is still person A on tuesday, but this has no relevance to airline security. If I fly on monday the airline doesn't care who I am on tuesday, because I'm off the plane.

Yet, it is apparently impossible to implement anything serious at airports...

Metal detectors are serious, x-raying luggage is serious, the machine they put me through in ATL or RDU which blew puffs of air on me and looked for explosives is serious, and reinforcing cockpit doors is serious. The problem with airline security is that it's Too serious now. We ask millions of people a year to take off their shoes because one numbnut one time tried, and failed, to use a shoe bomb. We don't let you take on breast milk or shampoo because you and your three chemist friends might sneak into the bathroom, build a fume hood, run controlled reactions for several hours, build a detonator out of...I don't know, toilet parts, and blow the plane up. That's ridiculous.

Heck, even at Disney World, they use thumbprints to validate their tickets.

Yes, but everyone knows DHS is a Mickey Mouse operation.

Heck, even at Disney World, they use thumbprints to validate their tickets.