drkitten,
Do you take more issue with the collecting of the fingerprints, or the accuracy of the data once taken?
Well, as you point out, the two are independent questions. But they're related.
If the data was considered correct, would it still not be worth the effort?
That depends somewhat on how the data is used. I've suggested for years, for example, that the easiest way to get a nuclear bomb into the United States is to hide it inside a bale of marijuana. Putting 100% accurate identity-detectors at every airport in the United States will do little when someone can just slip into a small boat in Toronto and be in Buffalo after four hours undetected. Depending upon the costs of the system, it still may not be cost-effective even with perfect accuracy.
But beyond that is the question of what happens once someone gets in.
If the method was considered foolproof (1:10,000,000), would you support identifying US citizens and those wishing to enter in this way, or would you consider it an infringement on personal privacy?
As a method of identifying people who wish entry, I wouldn't really have a problem with it. But the proposal goes substantially beyond that. For example, once I've entered the United States, that fact is recorded in a database that may be shared more or less at will with anyone. The government has a legitimate interest in making sure that I am who I say I am when I enter the country -- but I'm not sure that their interest extends to, for example, knowing where I stay when I'm in the States, or where I stayed when I was in France on my last trip. I think there's too much potential abuse in having that data on record and freely shared.