Sometimes sellers want to stay in their house when buyers are looking so they can eavesdrop on the conversation. Is there interest? Can they answer a question or offer clarifying information?
Or, if they left, they would anxiously await for their Realtor® to get some feedback on what the buyer prospects thought and if they were interested.
Now it is not necessary for them to wait.
Remember the old video cameras of years ago? Some were so heavy one risked injury just carrying it on a shoulder!
Today the ability to record as well as monitor in real time is less cumbersome and expensive.
Technology is inexpensive. Cameras are smaller. A laptop computer sitting on a desk could have a webcam doing a live feed. Or someone could be listening over the monitors in the baby's room. I have read that there are even stuffed animals that are really cameras. And security systems often provide live feeds to owners while they are away.