For a decade after the financial crisis the world economy’s problem was a lack of spending. Worried households paid down their debts, governments imposed austerity and wary firms held back investment, especially in physical capacity, while hiring from a seemingly infinite pool of workers. Now spending has come roaring back, as governments have stimulated the economy and consumers let rip. The surge in demand is so powerful that supply is struggling to keep up. Lorry drivers are getting signing bonuses, an armada of container ships is anchored off California waiting for ports to clear and energy prices are spiralling upwards....