Consider: Suppose for some reason you have income that the IRS doesn't know about. Maybe the 1099 form got lost in the mail, or there was a transcription error, or it was a payment from a foreign company, or the payer went out of business or died before sending in the tax forms, or whatever.

Anyway, now you get a pre-filled-in form from the IRS that doesn't include that income. What do you do? Whatever you answer, you're wrong.

Because if you say that you should report that income, as you are expected to do now, you have just said that even though the IRS fills out the forms for you, and you agree with them, you might still be expected to cough up extra money later if it turns out that the IRS didn't know about something.

On the other hand, if you say that you shouldn't report that income, you have just established the principle that if for some reason the IRS doesn't find out about it in time, you don't owe it. Which means you have just given the IRS the responsibility of tracking all financial transactions all the time, just in case.

Either way, I don't think this is a winning idea.

How would they know our business expenses, the car expenses, donations, etc. when they vary so much from year to year?

Forget to change one pre-filled number and the whole thing is wrong... not good.