Interesting question. I am in the UK, where there are a variety of courses and qualifications for people wishing to become counsellors or psychotherapists. I can only comment on what I know of training in the UK, and am obviously not going to say which course I am doing as I wish to stay anonymous.

I have not come across any UK courses that contain any optional modules whatsoever. They are not generally split into separate classes, with choices of what to take; you usually follow a compulsory programme and must have a very high attendance rate to complete this (usually around 80-85%).

In my case, learning about ethics and boundaries has not been a standalone class but a continuous, integral part of the learning. You can't really cover this off and consider it done, because it's something you're going to constantly be negotiating and thinking about. My course also requires me to sign up to a set of ethical guidelines. It would be strange if you didn't get to ask questions in class. Learning is usually through a mix of methods but not lectures in big halls as you learn in small groups.

So yes, we have talked specifically about why you can't have sex with clients.