When Megan Rothbauer suffered a heart attack at work in Wisconsin, she was rushed to hospital in an ambulance. The nearest hospital was "not in network", which left Ms Rothbauer with a $52,531.92 bill for her care. Had the ambulance driven a further three blocks to Meriter Hospital in Madison, the bill would have been a more modest $1,500. The incident laid bare the expensive complexity of the American healthcare system with patients finding that they are uncovered, despite paying hefty premiums, because of their policy's small print. In many cases the grounds for refusal hinge on whether the insurer accepts that the treatment is necessary and that decision is increasingly being made by artificial intelligence rather than a physician. It is leading to coverage being denied on an industrial scale. Much of the work is outsourced, with the biggest operator being EviCore, which ... uses AI to review " and in many cases turn down " doctors' requests for prior authorisation, guaranteeing to pay for treatment. The controversy over coverage denials was brought into sharp focus by the gunning down of UnitedHealthcare's chief executive Brian Thompson in Manhattan. The [words written on the] casings [of] the ammunition " "deny", "defend" and "depose" " are thought to refer to the tactics the insurance industry is accused of using to avoid paying out. UnitedHealthcare rejected one in three claims last year, about twice the industry average.