Tax on income - really?

Please enlighten me with your financial expertise but how exactly would that benefit anyone? For example tax is set at 10% for every business based on income. Manufacturer A has income of £1m per year, but 90% of that is costs involved in making the product leaving £100000 profit. A second manufacturer has the same turnover as manufacturer A but only 50% in costs leaving £500000 profit. By your reasoning manufacturer A should pay 100% of its profits in tax while manufacturer B only pays 20% of its profits.

Manufacturer A decides to shut down as they are not in business to make no money leading to more job losses and even less tax being paid while Manufacturer B ends up with masses of cash in the bank all tax free.

I am so glad you are not in charge of a complicated financial system like an economy.