Expectation of privacy at the dentist

I have been to a few dentist offices especially so I know not all are like this, but I do know a lot are. My current dentist is pretty open. There are full walls between the patient rooms, but the front room is open. It’s like a room w only three walls. Every time I’m there I can hear it all. This visit I heard the dental assistant ask for medications and dental history. Patient answered w some information that wasn’t even a little bit mine or anyone else’s business. As I was walking out, I saw her and realized I knew her. Why is patient privacy so important at the doctor’s office, but not the dentist?