Opinion: in his latest column, Dezeen editor-in-chief Marcus Fairs discusses why gated communities are "becoming the default setting in towns and cities around the world" and asks whether it matters who owns the land beneath our feet.

From the air, it’s easier to spot wealth than poverty. Climbing out of Cape Town International Airport the informal settlements soon become a blur but the private developments remain in crisp focus, their pristine loops of asphalt standing out like Nazca lines, the bulk of their road-straddling gatehouses unmissable and their clustered tricolours of lawn, pool and villa conspicuous against the dun landscape.

Later, descending into Johannesburg in darkness, the city lights reveal the same pattern: random, dull and fuzzy in the shack districts but bright and purposeful in the secure enclaves.  The British euphemistically call these developments “gated communities” but South African developers use the more straightforward “security estate”.

In one such as these, near Pretoria to the north, Oscar Pistorius felt safe enough behind high walls, razor wire, attack dogs and armed guards to sleep with the patio doors open (albeit with a gun under his bed and a cricket bat behind the bathroom door).

Pistorius lived on the Silver Woods Country Estate (shown in the aerial image above) - a “pres­ti­gious secu­rity estate” of 290 homes and still-vacant building plots set amid similar districts with names like Willow Acres and Faerie Glen. This still-growing Securicor suburb will eventually house 25,000 people.

The sleeping and bathing quarters at Casa Pistorius are now among the most familiar interior layouts of all time thanks to numerous media reconstructions of the night he shot and killed his girlfriend Reeva Steenkamp.

Yet the urban design of Silver Woods has hardly been discussed, even though its paranoia-driven features might provide the only mitigating circumstances in Pistorius’ favour: people who live in these places clearly fear for their lives.

Like most security estates, Silver Woods has a single point of entry and departure: a covered, manned and barriered gateway, bristling with CCTV and biometric scanners and resembling a sub-tropical Checkpoint Charlie. It is connected to the public domain but not of it.

The estate is “enclosed with a solid, elec­tri­fied secu­rity wall” and is planned “in such a way that it has the feel of a vil­lage.” All build­ing work is sub­ject to “a strict archi­tec­tural and aes­thet­ics spec­i­fi­ca­tion”.

Yet this is a village with no facilities on offer beyond raw security: no stores, playgrounds, bars or cafes. Residents have to journey by car for all their daily needs, or get them delivered. Hinting perhaps at the fearful priorities of its residents, the estate’s website boasts of its proximity to hospitals and medical clinics first of all, before listing the distance to local schools and shops. The location of the nearest police station is not regarded as a benefit worth mentioning.

While security estates respond to violent crime they do not solve it. Despite its precautions Silver Woods has suffered “incidents” in the past. Beneath a brief statement on its website from the Silver Woods management commiserating on the Valentine’s Day tragedy a woman called Colleen has commented: “We moved to the UK to avoid the crime. While liv­ing in a ‘secure’ sub­urb in Johan­nes­burg we expe­ri­enced many an inci­dent with regards safety, bur­glary etc. Our chil­dren were vic­tims of hijack­ing attempts as well.”

Developments like Silver Woods attract universal disdain from architectural writers and urbanists. They are seen as a betrayal of civilised values and an abandonment of design’s potential to benignly regulate behaviour in the urban environment. Former Guardian architecture critic Jonathan Glancey called gated communities a “social ill” and wrote: “It's time we opened our gates, and to shoo the fear away as we do.”

But they are becoming the default setting in towns and cities around the world – and not only for the wealthy. In the USA, the number of homes in developments secured by walls or fences grew 53 percent between 2001 and 2009 and now account for ten percent of all occupied homes.

Anna Minton’s 2009 book Ground Control documented the creeping privatisation of urban space in the UK and the USA but the book predates news of entire private cities being built in Guatemala and Honduras.

She updated the book in 2012 to include a new chapter on the London Olympic Park, which she described as “a divided landscape of privately owned, disconnected, high security gated enclaves side by side with enclaves of poverty which remain untouched by the wealth around them”. This, she writes, creates “a climate of fear and growing mistrust between people, which together with the undemocratic nature of these new private places, erodes civil society.” This paragraph makes Stratford sound like Johannesburg, which it most definitely is not.

I once found myself accidentally living in a gated community in London and the experience taught me of its benefits. Between signing the contract and moving into the flat the developer erected a high, spike-topped fence, electronic gates and unmissable CCTV arrays.

I was furious, until I found out that the other residents had demanded the improvements after numerous muggings in the dark cul-de-sac between the converted warehouses of our development. The over-conspicuous security measures caused mild resentment among neighbours on the other side of the fence but opportunistic crime ended immediately. We came to appreciate our ugly guardians. They were needed to overcome a fundamental design flaw – the spatially indefensible arrangement of the converted industrial buildings.

But even where there is no razor wire or guard, much of life takes place in monitored environments that require entry credentials. Concierged apartment blocks are types of security estates, arranged vertically rather than horizontally. Office buildings with swipe-card entrance systems are security estates.

The Tube and rail networks are security estates, as is a ticketed festival or conference (entry to the Design Indaba conference I was attending in Cape Town was via fingerprint scanner). Large private developments like Canary Wharf are gateless, city district-sized security estates.

What we think of as the public realm has in many places shrunk to a leaf skeleton of arteries that connect non-public realms. But does it really matter whether the land beneath your feet is owned by the state or by a corporation? And if the former is unable to guarantee the safety of its citizens, is it not understandable that they turn to the latter?