While working from home is less expensive for a company, why do employers not encourage working out of the office?

Companies worry about productivity and data breach. They think they if e mployees will work from home always, they will not work as hard as they would while at the office. And second, many large companies are really worried about their data. They think that if their employ ees will access company data outside, data migh t leak and it cause monetary damages in thousands of crores. So, that is why most companies do not allow work from home unless very critical. As far as I can determine working from home applies only to information workers.