More NC income tax craziness

I remedied my missing pages in the tax form problem easily by going to the NC Department of Revenue website and downloading the appropriate PDF.

The form does include the appropriate tax as a piece-wise linear function of taxable income. For taxpayers filing as a single, it's

T ( x )=	0.06 x	If 0<x<12,750.00
	765+0.07(x-12,750.00)	If 12,750.00<=x<60,000.00
	4072.50+0.0775(x-60,000.00)	If 60,000.00<=x<120,000.00
	8722.50+0.0825(x-120,000.00)	If 120,000.00<=x

However, immediately above all this information, is this statement:

"Caution: Use ONLY if your taxable income is $68,000 or more. If less use the North Carolina Tax Table beginning on Page 15."

1. If I should ONLY use the rate schedule if my income is $68,000 or more, why did they include the rate schedule information for income less than that? Two entire brackets are listed but can never be used.
   
   
2. Since the table only steps in $50 increments in taxable income, it is only an approximation to the function, and this is effectively a regressive tax. Suppose Antoine had taxable income of $67949, Bernard had taxable income of $67950, and Clarence had taxable income of $67999, and the filing status of each is single.
   
   1. According to the Tax Table, Clarence owes the same amount of tax ($4691) that Bernard does, despite earning $49 more than Bernard.
      
   2. Bernard owes $2.38 more than he should based on the rate schedule, whereas Clarence owes $1.43 less than he should based on the rate schedule.
      
   3. Antoine owes $4687 according to the table. Compare taxable income minus tax owed for Antoine and Bernard. Despite having earned one dollar more than Antoine in taxable income, Bernard actually has a smaller net income than Antoine. Sure, it's only $2 less, but still is this right?