I am an accountant (CPA) and I do see this sort of situation from time to time. To the best of my knowledge there is no such industry standard. Practices and policies do vary from one CPA to another. In the context of this message board, I don't want to say what others might to. I will only tell you what my policies and practices are:

I do evaluate and respond to notices sent by the IRS (or state tax authority) and advise the client what is (in my professional opinion) the best course of action under the circumstances. I often have to explain some procedural matters to the client.

Depending on the nature of the error, I do often try (in writing) to get the penalties reduced or abated, with some success. But there are also situations where I advise that the penalty must be paid.

In my experience in 25 years as an accountant I've never paid any penalty on behalf of a client. I do take care to prepare the tax returns in a manner which minimizes these situations. Not to say I'm perfect - I'm only human and I do occasionally make mistakes. Again, depending on the circumstances, I may rerun or even do an amended return at no charge to the client where I see the error is mine. But I also will charge a client for the same thing if it is a situation where the error is induced by something the client "forgot" to give me.