It really comes to simple process lot of companies operate. They buy some materials, they spend some labour to refine it, sell it, ship it. And what is above all these costs is profit. Taxing them on what they sold for, is not really sensible say with fuel, a low margin product.

Now what can be called cost is very reasonable question. Clearly dividends or stock buybacks should not be costs. And thus such spending should only come from post tax money...