Funerals, unlike weddings almost always have to start on time. Because people have a limited time to attend services, the funeral director wants to start the service on time out of respect for those who need to return to their jobs, or other responsibilities. In addition to the guests and funeral home staff, the cemetery and vault staff have schedules to meet and the ladies downstairs in the lunchroom are waiting to serve lunch and be on their way.
Most important of all, however, is the family. Here's what happens when everyone shows up right before the service and wants to see them. The family feels compelled to visit with everyone who has come to support them, but they also need to say their goodbyes before gathering with Pastor for a prayer and a moment to catch their breath before the service starts. The result, unfortunately is that the family either feels bad for not visiting with guests, or they miss their chance to properly say their goodbyes.