The fact that our government doesn't have the collective intelligence to just mail the tax bill using the information it already knows, with the option for the recipient to submit corrections/deductions, is a testament to the utter failure of governance in the US. Fortunately having an ineffective government can often be a feature instead of a bug.
Idk. I think the IRS gets the better end of the stick here. They have you tell them how much you owe. If you report more than they knew about great they made money. If you tell them less than they knew about, then they'll audit you assuming the difference is large enough (and there being a high likelihood of winning)
If they precalculated your taxes and sent you a bill (or refund) it would (a) be easier, (b) be more accurate and (c) encourage simplification of the entire system. I consider that both more effective and more fair.