MLSs, Associations, real estate offices, brokers and agents are all involved in showings in some way. Whatever the process is where you are, requests are being made and responded to, calendars are being updated, and schedules are set. What does all this cost?
One of the great things about residential real estate is that agents can decide how to run their businesses. You can plan your schedule based on other commitments, which is harder to do in a traditional 9-5 job; you can decide how to market your listings; you can choose how many calls to make; you can take a sales course to improve your skills; you can leave one brokerage and join another.
It's time consuming to call showing agents to ask about the showing; it's equally challenging for the showing agent, who may have taken their buyer to view several listings, to remember which listing you're talking about.