Correct: if one takes as basis not the Bruttolohn but the total cost for the company, the sum of taxes and mandatory social contribution can very well reach the half of the income. The method of splitting employer-side and employee-side deductions seems just there to hide this fact.

Most taxes are deducted when money is transferred between two parties. The view that one party pays it all (Brutto-Netto and VAT) seems wrong to me.

I anyway doubt that the wages would be at the same standard if there wouldn't be any deductions (from the beginning). Wages in expensive cities are higher because the cost of living must be matched. Similarly salary negotiations account for deductions. Nobody wants a job that doesn't pay the bills.