[thejeff]

I'll agree with your single mom example. It's a silly system. A more graduated drop as you earned more would make far more sense. And universal health care would make a lot of those issues go away. Having health care tied to employment leads to a lot of problems and results in a system that costs more and produces worse results than other "developed" countries.

As for your university example, any decent sized bureaucracy works the same way. Any good sized company is full of politicking over departmental budgets and personnel. More money translates into more importance.

More importantly, I'm not sure how a flat tax addresses any of your concerns. I assume you're talking about a single income tax rate with no (or minimal) exemptions or deductions? Simplifying parts of the tax code would have benefits, but I don't see what that has to do with the actual flat part of the flat tax. You could equally well remove the deductions and keep graduated tax rates, or have a single rate with all the complex deductions.
A flat tax would also raise rates at the lower end and, especially if you also remove the deductions for her children, make your example single mom's situation worse.