How can you establish an effective tax on revenue when business expenses vary so widely? And if a business increases it's expenses through nonsense like 'consulting fees' it will artificially increase their expenses

It would result in the same thing as op just said. They would adjust prices to compensate to keep their profit margins similar. The only way to force their hand is to take a measure of control of the company itself. Force it to set a limit on price in relation to CPI, have windfall tax on profits that far exceed what they make, have quotas for refined oil they can process/sell

The govt would have to basically control the price and quantity. This is real Socialism. But outside of that there is no real way to force companies to pay their 'fair share' in a capitalist system