One big reason is price. Google charges $50 a year for each person using its product, a price that has not changed since it made its commercial debut, even though Google has added features. In 2012, for example, Google added the ability to work on a computer not connected to the Internet, as well as security and data management that comply with more stringent European standards. That made it much easier to sell the product to multinationals and companies in Europe.
via Google Apps Moving Onto Microsoft’s Business Turf – NYTimes.com.