In theory yes, in practice no.  

There are many ways under the tax code to avoid or defer taxes that rapidly diminish or disappear as they move down the income scale.  It is not very difficult for high income earners to pay proportionally less than lower income earners.

Adam Smith was talking of fairness, not economics, when he included his opinion on taxation in his treatise. For a more contemporary view Peter Drucker believed that top salaries should not exceed 20x those of the average worker which is no doubt much more punitive than Smith ever envisaged. 

A growing economy should improve, even if slowly, opportunity, wages, benefits, working conditions, security and living standards for the majority. In order for democracy to flourish government must serve the common good by ensuring that the benefits of growth are widely shared and not  sequestered by the few.