In businesses, income can refer to a company’s remaining revenues after all expenses and taxes have been paid.
http://www.investopedia.com/terms/i/income.asp
Income is not revenue.
So, exceptions for businesses ARE allowed - the costs to generate revenue such as mortgages, building improvements, etc...!
But, to the average American, they are just going to get screwed at a flat 10% - regardless of their need and necessity to have a mortgage, make building improvements, etc...!
Once again, we are opening the door to loopholes, interpretations, and other ways to avoid taxes and allow the government to once again start building a million-page tax code - one lobbyist at a time.
I have no objection to writing off the legitimate costs of doing business and taxing net income. A company car and a weekend hideout for the CEO are NOT legitimate business expenses, for example.