That's why taxes must be proportional too. The state spends X euro, the productive economy pays Y euro of salaries+dividends, therefore everybody pays incomeX/Y

That's why taxes must be proportional too. The state spends X euro, the productive economy pays Y euro of salaries+dividends, therefore everybody pays incomeX/Y of taxes. X/Y is the income tax rate. Or if you prefer to tax sales, with Z being the total amount of sales, priceX/Z. X/Z is the VAT rate.