Past a certain point, age has little to do with prudence. There are rational and knowledgable teenagers just as there are middle-aged dullards.
One must also keep in mind that the man of the 18th century achieved the necessary milestones to become a self-sufficient adult by his late teens. He will have already lived a full life at the age his 21st century counterpart crosses the starting line.
Of course. Although being self-sufficient does not mean that you have a fully developed brain and cognition, either.
And absolutely, rational and knowledgeable is certain. But we seem to treat their edicts as the height of infallible perfection in government, and view it as anathema to even suggest ideas that don't precisely align with their statements.
One must also keep in mind that the man of the 18th century achieved the necessary milestones to become a self-sufficient adult by his late teens. He will have already lived a full life at the age his 21st century counterpart crosses the starting line.