That is the silly part. These people keep saying this stuff will keep us safe, but it hasn't proven to be so. The last couple of incidents show the same failure as 911. We had the information already, but decided not to act on it for some reason. Data gathering has never really been the problem.
The problem is one of data analysis and false positives. We can gather the data - that's automated. The problem is processing the data.
Then, the thing is, at the indicator levels you get for a terrorist, there's a LOT of false positives. We've seen it here when the government publishes some 'indicators that somebody might be a militia member' and we trip half to three-quarters of them.
Investigating a 'trip' is expensive, and we're spending so much money just collecting all this data that we can't afford to follow up all of them, knowing full well that the vast majority will be false-positives. So we have terrorists slip through.