Redshift is a proper example of what happens when developers expect the OS to run some specific program. In this case,redshiftexpects.servicefiles to be present, and simply fails without them:

$ redshift
Trying location provider `geoclue'...
Unable to obtain master client: The name org.freedesktop.Geoclue.Master was not provided by any .service files
Failed to start provider geoclue.
Trying next provider...
Trying location provider `manual'...
Latitude and longitude must be set.