I think you should talk to her about this issue. I also agree about it being part of the culture, but that does not make it OK. If it consistent, you should bring it up. I am not sure of the response you will get, but it does affect your feeling of being respected by the doctor which is not a good thing to have in treatment. Mental health people track time differently than attorneys and sometime just need to be reminded of that.
I don't think she will change her timing. I've been with her for four years. I do though feel humiliated when she arrives 20 minutes late or is in her office and not even with another patient.