From a security standpoint, it seems like there's a problem treating everyone's social security number as if it's some kind of secret key.

Has there been any real discussion about alternatives to the present system? How else could authentication work for opening a bank account?

I imagine that the present system survives (1) because of inertia, and (2) because it doesn't require much infrastructure and so it's relatively cheap.

Maybe the next step is something like putting a chip into driver's licenses and ID cards nationwide?