Basically, politicians want to be seen as "doing something about the problem" for any problem you could think of. And the tax code is their preferred mechanism. So we have a huge mortgage interest deduction which is supposedly to encourage homeownership, deductions for home office expenses, the alternative minimum tax which is supposed to prevent millionaires from not paying taxes, and on and on. Most of these rules don't really do what they're supposed to do. For example, Warren Buffet pays very little tax, despite all the AMT's complexity. Tax breaks for homeownership just get reflected in the price of homes, serving to make them less affordable, not more.

Democrats oppose reducing taxes on principle. And Republicans talk a lot about reducing taxes, but usually find more interesting things to do once they're actually in office. Special interest groups of all kinds lobby heavily for their own distortions of the tax code, and the average voter has little idea what is going on.

The people who get hurt the most by all this are the middle class. The very poor have nothing to take, and generally pay either no or very little tax. The very rich have professionals to handle all this.