The Wall - what is it good for?

My dog takes me out for a daily walk around my  neighborhood, she enjoys stopping at posts, fire hydrants and walls. We've noticed that there are more and more walls being erected around many new homes. I wondered if this is a new architectural style, owners philosophy, fear, or a new quality of life in an urban setting;  people behind their walls.

Wall have been around for centuries, we all know about the powerful and mighty "Great wall of China". Constructed to keep conquering armies at bay.

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Great Wall; Google

The infamous Berlin wall, below, imprisoned its citizens under penalty of death, in East Berlin for
decades.

Building  the Berlin wall imprisoning it's citizens. images.jpb

This is what's left of the infamous Berlin wall, a memorial. A testimonial of the cruelty of men towards his own brother. Tourist can peek through the wall towards East Berlin

The opprobrious wall at the US-Mexico border, below, divides but it can-not conquer. Vendor lean against it, stray dogs use it, young people etch their feeling on it. Hungry Mexicans wait for darkness to conquer it. Americans implement contingency plans, diagrams and night maneuvers to stop them.

Walls are made to keep people out, keep other people in. Keep pets safe, keep stray animals out. They also keep your things secured, away from prying eyes. Walls keep secrets from neighbors, also hide  nefarious actions. Walls are a sanctuary for their owners, keep traffic noise down and noisy mischievous  persons away. Antisocial personalities hide behind walls, wall are a canvas, gatherers of information.Walls also substantiate our fears.

A couple of block from my home this wall is being constructed, definitely, to keep people out. It clearly says
you... are not welcome.

This living, Eco-friendly, wall  is on the way to my sons school. It definitely says do not disturb, leave us alone, we don't want to know you. It's made to keep people in. We have never seen the residents.

This wall was constructed to keep adult toys safe. There is a fishing boat covered by a blue tarp, sports cars, motorcycles and bicycles. All covered against inclement weather and prying eyes.

I was thinking of putting up my own wall but... But I have nothing to hide, and no one to keep out.