India terrorist attack lessons learned

Security expert Bruce Schneier lists four lessons learned from the Mumbai terrorist attacks:

• Low-tech is very effective. Movie-plot threats — terrorists with crop dusters, terrorists with biological agents, terrorists targeting our water supplies — might be what people worry about, but a bunch of trained ... men with guns and grenades is all they needed.
• At the same time, the attacks were surprisingly ineffective. I can't find exact numbers, but it seems there were about 18 terrorists. The latest toll is 195 dead, 235 wounded. That's 11 dead, 13 wounded, per terrorist. As horrible as the reality is, that's much less than you might have thought if you imagined the movie in your head. Reality is different from the movies.
• Even so, terrorism is rare. If a bunch of men with guns and grenades is all they really need, then why isn't this sort of terrorism more common? Why not in the U.S., where it's easy to get hold of weapons? It's because terrorism is very, very rare.
• Specific countermeasures don't help against these attacks. None of the high-priced countermeasures that defend against specific tactics and specific targets made, or would have made, any difference: photo ID checks, confiscating liquids at airports, fingerprinting foreigners at the border, bag screening on public transportation, anything. Even metal detectors and threat warnings didn't do any good.