With so many having learned to live off the government during the recession, combined with an increasing inability of workers to pass drug tests, employers are finding it difficult to find qualified workers to fill jobs. Productivity growth has been weak since the recession ended in 2009. It grew just 1.2 percent a year, on average, in the past decade. That’s less than half the growth rate before the recession. One reason productivity has been so sluggish is that companies haven’t invested much in machinery, technology and other equipment that could boost workers’ output. The result? October jobs report showed that pay gains remain sluggish, and the explanations include weak worker productivity and a still-low proportion of adults with jobs. These are long-running trends that still bedevil the economy despite its steady improvement.