I've long known that any large collection of data by the government, or any agency, is something to be nervous about. Here is an article that demonstrates exactly why this is. The long and short of it is that the incentive to steal data is increased by the square of the amount of data to be stolen.

This means that in order to prevent a government database containing detailed information on every citizen from being compromised, the security would need to be (essentially) exponentially better than that which a private company uses to secure their own database of customer information. We've all seen how many private companies' data is compromised, so what makes us think that the government is capable of providing this sort of security?

I work in a group responsible for securing customers' payment information and I know what kind of effort we put into keeping it safe. I can then tell you that the security practices which would be needed to secure any such national identification database would be so cumbersome as to render that data useless. We can therefor be sure that no sufficient security measures are in place on any such national databases, nor will they be on any future, larger, databases.