Agreed! The last time I looked, Eighteen was the age of Adulthood in the U.S.! What was Sarah going to do, send her to her room?!
Well, 18 year old Bristol may be an adult, but she’s living like a child in her parents’ house, and they can set any rules and restrictions they see fit. I would think that just mere consideration for the household would cause Bristol to let them know their day would be interrupted with a camera crew, etc.