"Second, I also don't get how people trust strangers with intimate details of their thought life."
Pretty simple: legal barriers to revealing that information creates an open space for discussing those thoughts that you don't feel comfortable revealing to friends or family.
That's what I don't get, you have such grear confidence in legal barriers but keep in mind, your therapist also has assistants/staff sometimes, they take notes that could get leaked/stolem, they could get hacked if it is digitally stored,etc...
I mean, some shit I wouldn't even dare speak out loud anywhere near a smartphone or network connected device. These days, you say the wrong thing and they'll put you in a 72hr psych hold and ruin your life (having to explain that to your work/spouse!).
Beyond that, these people are experts at manipulation (to an end they consider good), they could take that information and get you to think in a way that is undesirable to you.it could be life changing but it that change does not have to be positive. Your putting your faith in a lot if humans and a lot of processes and checks working right.
Pretty simple: legal barriers to revealing that information creates an open space for discussing those thoughts that you don't feel comfortable revealing to friends or family.