Ask HN: How do OpenDoor viewings work?

I'm curious how they can ensure the security of their properties during viewings, where the potential buyer views the unit in a timely manner and locks up the property when they leave. In the traditional real-estate market, you would use a physical key box with a 4-digit code to get the key and it is out of good faith that you're to lock up and place the key back in the box.

Since they take ownership of the house and restart the buying process, do they replace the locks with Smart Locks to work with the access code where they can ultimately control access to the house?

I've never used OpenDoor but it seems like they've eased the process for potential buyers to complete a viewing of a property on their own time. After looking for a condo for the past 6 months and having over 30+ unanswered viewing requests I felt the pain from a renters perspective.