The U.S.A.--The United States of Afraid?

Great Wall of China

All the political talk about building a wall between us and Mexico is more than disturbing, considering history.
Remember, "Mr. Gorbachev, tear down that wall"? Now, we're saying, "Mr. Trump, Build that wall."
Consider the historic walls, many designed to keep people out, or is it to keep people in?  
What's the difference? A matter of perception, perhaps. Aren't they all built on fear? Today there is a story on the front page of the New York Times about Hungary building a fence to keep immigrants out. 

What kind of mindset does it create

for those living behind a wall?

Consider our high-priced "gated communities," many with guards at the gates and medieval architecture. All the houses are cookie cutter and all the people living inside think alike--perhaps medievally, excluding those who are different. 
You become hostages in your own land, thinking like medieval people seeking refuge in a stone castle for protection against the barbarians. I understand armed guards at military gates, but those living inside are not living in fear.
Has the U.S.A. become the United States of Afraid?
And, in the long span of history, have any of these walls actually worked? 

Here are some other famous walls, in historical order.

Hadrian's Wall, England

Maginot Line, France

Berlin Wall

North-South Korea

Israel

U.S.-Mexico