TO THE sound of electric guitars, heavily armed police officers fire assault rifles, drive squad cars fast and pull their guns on fleeing crooks. “Are you qualified to join the thin blue line?” asks a narrator, in the sort of breathless voice you might expect in a trailer for “Fast & Furious 7”. The advert’s aim is not to sell movie tickets, however, but to recruit police officers in Gainesville, a city of 127,000 in Florida.

Would-be cops who take this video seriously are likely to be disappointed. The reality of the job, as one officer from a large west-coast agency explains, is far less glamorous. “The public want us to come up and deal with a neighbour who is mowing their lawn at 3am. They want us to deal with their disruptive child. They want us to deal with the crazy person who is walking down the street shouting.” As crime has fallen across America since the 1990s, policing has shifted more towards social work than the drama seen on TV. Police culture, however, has not caught up.

The gap may help to explain why American police are so embattled. The latest controversy is the death of Freddie Gray, a 25-year-old man from Baltimore who died on April 19th after being arrested (six officers have since been suspended). That followed the killing on April 4th in South Carolina of a 50-year-old man, Walter Scott, who was shot in the back by a police officer after running away from his car (the officer was charged with murder after a video of the killing emerged). In another case in Tulsa on April 2nd, a 73-year-old reserve police officer killed a man when he accidentally fired his gun instead of his taser. All three victims were black.

No one knows how many people die in contact with America’s roughly 18,000 law-enforcement agencies. The FBI publishes reports, but police forces are not required to submit data. The incomplete FBI figures show that at least 461 people died in “justifiable homicides” in 2013, an increase of 33% since 2005. Other sources suggest the true number could be as high as twice that. In Britain, by contrast, police shot and killed precisely no one in 2013.

American police resort to violence more partly because they meet it more. “We’ve never had a population who are so well-armed,” points out Ron Teachman, the chief of police in South Bend, Indiana. Twenty-six police officers were killed with guns in the line of duty in 2013, far more than in any other rich country. “When you go to a police academy, the first thing they say to you is that it’s dangerous and you could get killed out there,” says Jim Bueermann, a retired police chief and the head of the Police Foundation, a think-tank.

Yet fewer police officers are killed now than in the past, and the number who are shot is less than the number who die in traffic accidents. Over time, suggests Mr Bueermann, a justified alertness to danger may have warped into a belief that the swift use of force is the only thing keeping cops safe. At its worst, this manifests itself in a fiercely defensive culture. For example, in Seattle last year more than 100 cops sued the Department of Justice to protest against a revised use-of-force policy, arguing that it would cripple morale and endanger cops (the case, which was not supported by the city’s police union, was thrown out).

Talking about Eric Garner, a bootleg-cigarette-seller who died in New York last year when a policeman put him into a chokehold, one street cop argues that the police should not be blamed: “He was continuously fighting with the officer. What really killed him?” This cop says that officers have to subdue people forcefully, because the alternative is to let criminals do as they please. If there is a problem, he says, it is that too many cops are not well trained in how to use force safely and so rely on brute violence or, worse, their guns. Another, a lieutenant, adds that he thinks that “the public needs to be educated better. We can’t let our guard down because we’re making ourselves less safe.”

Yet force is often used to subdue low-level offenders like Garner, not just dangerous people. And it is unclear that armed policing is the best way to deal with all problems. At least half of all Americans shot and killed by police each year are mentally ill, says a report from the Treatment Advocacy Centre and the National Sheriffs’ Association. Police officers also spend time dealing with drug addicts, domestic disputes and, increasingly, the enforcement of civil penalties against people who have not paid motoring fines or child support. Such people are not muggers or rapists, yet cops often treat everyone as a threat.

What is the solution? Many cops are pessimistic: they feel they are scapegoated for social problems (“You’re all fucking unreasonable!” exclaims one.) But improvements are being made. Sue Rahr, the director of Washington state’s police academy, says that cops need to be taught how to talk to people again. “When you approach a situation like RoboCop, you’re going to create hostility that wasn’t there before”. Since 2012, the state’s training has emphasised that people can be persuaded to obey commands, not just forced to. Military-style drills have been ditched. Ms Rahr now serves on a task force created by Barack Obama to spread such ideas.

Sadly, as the Gainesville video shows, not every police force is catching on. And as Ms Rahr admits, if you try to recruit cops by telling them they are social workers, fewer may apply. At least part of the glamour of the job is the promise that you get the chance to use violence against bad people in a way that ordinary civilians never can, except in video games.