Your personal income is for yourself. A corporation's revenue that goes towards expenses is for the customer. Say you buy a gold at $700, and turn it into gold

Your personal income is for yourself. A corporation's revenue that goes towards expenses is for the customer. Say you buy a gold at $700, and turn it into gold jewelry that you sell it for a $1000. If the tax rate is 30%, and the jeweler is taxed on the revenue, the jeweler would have made no money at all! If you do tax the expenses, it would have to be passed straight to the consumer.