It really doesn't, at least in the legal sense. Managers have wide legal latitude to run the business as they think best. However, in practice corporate boards tend to vote the short-term numbers, which combined with decreasing CEO tenure is a strong incentive for CEOs to do short-term, exploitative things. That's not always the case, though. Bezos, for example, built Amazon to its juggernaut status by ignoring the short terms numbers and doing a lot of long-term investment with a focus on increasing customer value. It's only lately that it's turned to exploiting its customers as well.