What is absurd is your age old differentiation between "unearned" income and "earned" income.
If a bank loans you money, they expect the money back, plus interest. The interest is a cost to you for borrowing the money, and business income to the bank for being in the business of lending you money.
When a person invests in a business in the form of stock purchases, they are effectively lending that business money. Like a bank, the investor has a reasonable expectation to be paid for loaning their money to the business. The resulting investment income is no more "unearned" than is the money banks earn for loaning individuals money.
We agree on one principle: the tax system should be as efficient and as painless as possible. But you seem to think efficient is making it painless as possible for low and middle income by screwing with what you call unearned income. Problem is many middle income people have investment income, so your aim is lousy when it comes to taxing investment income. Second, treating people unequally just because you think they can afford it is not what this country is supposed to be about. Third, the simplest (ie: least paperwork, least number of rules to worry about, simplest calculations to find one's appropriate tax burden) is also the most efficient because making complex tax codes wastes time (and time is money even in government) creates an unnecessarily large bureaucracy (wasting more money) and depresses revenues by discouraging investment from income brackets other than the highest.
As for what "every civilized nation" believe in, I don't give a ripe fart. We need to be doing what is best for our nation, and operating government - to include the tax system - according to the principles our society is founded on. Treating people differently according to economic class is no different than allowing people to be treated different because of any other distinguishing characteristic they display that can be used to separate people into groups. It is wrong to treat people unequally for any reason - that is a base principle of our society. Therefore it is wrong to treat people unequally for economic reasons.