At one telling moment in this unnerving and convincing book, Antony Loewenstein quotes the managing director of one of the many private military companies (“PMCs”) working in Afghanistan. The United States, says “Jack”, “is not capable of running empires”. Instead, western governments outsource imperialism to people like him in a variety of organisations – Halliburton, G4S, Serco and Capita are the best known of a long list – which make their money from incarceration, the “processing” of asylum seekers or the provision of private “security” in conflict zones. No longer able to sustain itself by selling dreams, capitalism now thrives on the management of nightmares. Even the provision of disaster relief is transformed into profit.

Disaster Capitalism takes us on a journey around the victims of this system: Greece, Afghanistan, Haiti and Papua New Guinea. It then turns its attention to the centres of outsourcing such as the US, the UK and Loewenstein’s native Australia. It charts the consequences of a double crisis: turmoil in the economic system following the financial crash, and the migration that is the unsurprising effect of the wars in Iraq, Libya, Afghanistan, Syria and elsewhere. Greece, at the heart of the eastern Mediterranean, has been the victim of both at once. Loewenstein notes that despite Syriza’s promises to challenge austerity, the state’s hands are tied not only by the troika, but by a wave of popular xenophobia, supported by a supine media. So, instead, non-state forces are stepping in: he visits the medical centres set up by leftwing volunteers to help the victims of both crises, and, more depressingly, the Greeks-only food handouts organised by Golden Dawn.

Similarly, in his account of the “relief” that followed the Haitian earthquake of January 2010, Loewenstein argues that the people of Port-au-Prince were able to organise themselves to respond to the devastation – “makeshift clinics were established”, and “young men and women worked to clear the rubble with their bare hands”. After this, however, the international response was quickly monetised, or, to quote the typically direct words of then-US ambassador to Haiti, Kenneth Merten, “the gold rush is on”. The response to the disaster combined outsourcing to the largely USAID-funded contractor Chemonics, with American and Korean companies building factories to produce consumer goods for the western market while paying workers well below the already minuscule Haitian minimum wage. A new development was the intervention of celebrity-backed NGOs. The philanthropic efforts of Wyclef Jean, Sean Penn, Bill Clinton and Bill Gates come in for particularly sharp criticism as unaccountable and aloof. All this activity rests, according to Loewenstein, on a perception of Haitians as incapable of looking after themselves, a view his account attempts to challenge. As Pierre Justinvil, the deputy mayor of Cap Haitien, puts it, surveying a housing development built by a Minnesota-based company, “I personally, with my own hands, have just built a whole school for less than the cost of one of the houses, and more quickly.”

The irony is that Britain, the US and Australia are now inflicting on themselves many of the devastations they have visited on other countries. This is visible in the US’s immense privatised prison system, providing a convict labour force which, the author estimates, is bigger than the Soviet Gulag at its early 1950s height. The militarised response to the Ferguson protests last year are another example: the tooled-up, armour-plated local police “looked like they were equipped to fight insurgents in Iraq”. And they were: a programme had sold off excess military equipment, provided in the first instance by private companies, to local police departments.

In the UK, Loewenstein tracks the results of a decision to open up emergency accommodation for asylum seekers to our beloved volume housebuilders: “Taylor Wimpey, Barratt Homes, Persimmon, Bellway, Redrow, Bovis, Crest Nicholson”. Meanwhile, Britain has become a major exporter of outsourcing, with G4S and Serco being worldwide leaders in the field.

Disaster capitalism comes across as a thuggish operation, largely based on low-wage, low-conditions work where sensitivity to the often vulnerable people being “cared” for is not a major priority. At a nightclub full of PMC staff in Afghanistan, Loewenstein is “reminded of a comment made by a human rights advocate in Kabul, that if you go to a party in the city, ‘a quarter of the men will have no necks’”, a consequence of widespread steroid use. Everyone is dehumanised by what another outsourcer calls “the human warehousing business”.

One major strength of the book is its interviews. We meet a succession of nice, apparently open spokespeople for outsourcers and mercenaries, and even a well-mannered physicist and active member of Golden Dawn. He lets them speak with their own breathtakingly cynical words. Loewenstein is unashamedly partisan, though, especially in the chapter on the Bougainville province of Papua New Guinea, where a mass revolt removed the privatised mining corporation Rio Tinto from the area, leaving it reliant – by popular demand, it would seem – on subsistence agriculture. The corporations are coming back to Bougainville, and Loewenstein gives a sympathetic account of the forces trying to stop them, noting the horrendous ecological record of the companies in question. These divisions can be a little too neat.

After a particularly harrowing account of Australia’s “Pacific solution” to migration (ie, put them all on an island), Disaster Capitalism concludes with a rather pro forma rousing address, insisting that “resistance is never futile” and pointing to those places – small French towns, the city of Hamburg – that have managed to reverse outsourcing and privatisation. That’s fair enough, but as the accounts from Haiti and Papua New Guinea make clear, the system Loewenstein describes thrives by presenting itself as the only possible conduit for development and change. By placing, say, Rio Tinto on the one side and subsistence farming on the other, the choice becomes either virtuous tradition or hyper-exploitation. A model of development that could challenge these ruthless practices would make Disaster Capitalism a lot more convincing, but as an eyewitness account of the vultures’ activities around the world, it does provide a useful warning.

• Owen Hatherley’s Landscapes of Communism is published by Allen Lane. To order Disaster Capitalism for £12.99 (RRP £16.99) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.