After a year of holding back on new hires, companies from tech and transportation to defense now say they need more people to work alongside AIAmerica’s biggest companies say they might need more people after all. For months, major employers treated hiring as an expensive last resort. Now, a shift is emerging across industries. Companies ranging from railroad giant CSX to Google parent Alphabet GOOGL have told investors in recent days that they plan to hire to meet growth goals or to seize on emerging technologies.The push to expand head count, at least modestly, is a reversal from the prevailing...