I don't think it's related to national ID system though. The Social Security Number (or Tax Identification Number for non-citizen non-residents) does serve as a national ID for tax purposes. The IRS certainly already does have your W2's and does know who you are, that's not an issue.
The main issue is what the OP is about, that the US was considering creating such a system, but the tax prep software people lobbied against it.
I also wonder how much of an issue is the crazy complexity of the US tax code; it seems ridiculously complex to me, even for people without complicated or large income, I suspect it's a lot simpler in Spain. But this is just me guessing.
I don't think it's related to national ID system though. The Social Security Number (or Tax Identification Number for non-citizen non-residents) does serve as a national ID for tax purposes. The IRS certainly already does have your W2's and does know who you are, that's not an issue.
The main issue is what the OP is about, that the US was considering creating such a system, but the tax prep software people lobbied against it.
I also wonder how much of an issue is the crazy complexity of the US tax code; it seems ridiculously complex to me, even for people without complicated or large income, I suspect it's a lot simpler in Spain. But this is just me guessing.