In the UK you don't have to file a tax return unless you have unusual finances (e.g. are self employed), and sales tax is includes in the advertised sale price of items.
We still have to oay taxes of course, but they are much less annoying!
EDIT: I should clarify that I don't mean that the particular individuals that reinforce this particular law wrote the tax bill, I see them mostly as an amorphous class of rouges much as you might regard Annonymous.
But you said that tax complexity was foisted on people in order to make them be more in favor of lower taxes for the rich. I was merely pointing out that this wasn't really the case in the most recent tax bill as complexity for many typical filers was generally reduced.
We should end automatic withholding and let everyone pay their taxes on April 15.
You also propose a very poor solution. A large % of Americans are not disciplined enough with their budgeting to save such a large % of their income to write a single check every year. A lot of folks simply wouldn't have the money when it came due. What would you do then?
Work by people like Thaler and Sunstein is encouraging because it helps us improve our skills in a systematic manner so it can better scale.