To be fair, paying taxes if all you're doing is receiving income from an employer isn't that bad. There's a simple form for it. Where it gets bad is the stuff your employer doesn't know about:
* Investment income
* House or other capital sales or purchases
* Stock option purchases or sales
* Child custody, dependents
etc. I don't see how any country's tax code would capture these income or loss streams without some manual filing process.
Most of what you mention is filed automatically for me, here in Denmark. I think the only thing normal employees regularly file manually here is kms driven to and from work, which gives a tax deduction (kørselsgodtgørelse).
Perhaps these don’t need to be lumped into a single tax return and can instead be handled independently by the appropriate institutions — brokerages deducting tax on investments, closing agents deducting tax on house sales, IRS mailing a check each year for dependents, and so on.
Sibling comments suggest that other countries successfully automate much of their taxes.
Just to add, regarding the "single tax return": In Finland many of the remaining have-to-input-manually things (e.g. kotitalousvähennys, tax credit for household expenses) can be reported on the tax web portal at any time.
* Investment income
* House or other capital sales or purchases
* Stock option purchases or sales
* Child custody, dependents
etc. I don't see how any country's tax code would capture these income or loss streams without some manual filing process.