The income tax system has costs to business even when there is zero income tax liability... plenty of costs.
Even if there's a lot of success, there can be zero tax liability AND a lot of money spent on tax planning and such...including making non-productive decisions solely for tax purposes.
That aside, I don't understand your position on why income taxes "are different" just because the amount due is not known ahead of time - and that difference means that the tax is not paid from sales revenue. Can you elaborate?
I have described how profit is a residual and it is on this residual that income taxes are calculated. Income taxes do not enter into the calculations determining the cost of the product. However, the costs of determining the profit and income taxes ARE true costs as they are there whether there is a tax paid on not.
Prices are determined by market conditions thus one can never know whether there will be a profit or not. If the market does not allow a price high enough for a profit then there is no tax. Hence it is not a "cost" as are the components of the product which have been paid.
By your logic income tax would be a cost if there is a profit but NOT a cost if there is none. Hence it cannot be compared to a true cost which is a cost in either case.