Programs and services are different kinds of entities. A program is a work that you can execute; a service is an activity that you might interact with. For programs, we make a distinction between free and nonfree (proprietary). More precisely, this distinction applies to a program that you have a copy of: either you have the four freedoms for your copy or you don't. An activity (such as a service) doesn't exist in the form of copies, so it's not possible to have a copy or to make copies. As a result, the four freedoms that define free software don't make sense for services.