not completely true where I live

Minors DO have some doctor-patient confidentiality, particularly with respect to the authorities (they have the same as adults, basically: If the doc thinks anyone is being hurt, he can and/or must report it, otherwise, he must not).

The family-confidentiality depends in large part on the minor's age and the professional's judgement of whether telling the family would IMPROVE or HARM the minor's situation. Overall, a doc is much more free to talk to the parents of an 8yo than of a 16yo.

To put it another way: Your "if the doc finds it suitable" remark is pretty much on the money, BUT it implies that there IS no difference due to age, but de facto, there is, because it's much more likely a doc would "find it suitable" if the minor were 8 than 16.