What you really have to do, in both writing and acting, is more subtle and difficult. It has to become an organic part of the narrative/performance Any example you give is always going to sound like indicating, since it is extracted from that overall flow. If you've crossed out "he was nervous" and wrote instead "his pulse raced", you haven't improved it by much, if anything. But if you're fully visualizing the scene, from whatever POV you've been using so far, you can seek out the next detail and write that as the next sentence.
The essence of "show don't tell" is to be active rather than passive. Talking about feelings, or even indicating feelings, is less active than saying how they act on those feelings. The more specific their actions, the more the reader will internalize the feelings as they live it with the character, even -- or perhaps especially -- when being told from a viewpoint that wouldn't give them access to internals like pulse rate. Movies are exciting without getting any of that information directly.
If someone is a true literary master they may come closer to bridging that gap, but you always leave a lot of ambiguity on the table that way. Sometimes that ambiguity is fine, and allows the reader to add their own interpretations and the outcome may well be better for it, but if you have specific things you want to convey, it can be incredibly hard to convey even very simple things without telling.
I got incredibly cynical of that after going through literary analysis at school and seeing just how contrived a lot of the attempts at analysis were. Even when trying to analyse works line by line the outcomes are often extremely dubious (or directly contradicted by the author); I don't think even most world renowned authors are capable of unambiguously putting through particularly complex messages without telling. Often it's hard enough to get the message through when it is incredibly explicit.
In the end it's a matter of communicating what you want to the intended audience. 'show don't tell' is a tool to do it. but you're right, not everything is a nail you need to hit with that hammer.
As Campbell set it out, it’s less a singular structure than a catalog of common scenes and archetypes in heroic myths, not all of which might appear in any given story. It’s the overall arc of “hero enters magical world of story -> overcomes trial -> returns with power to grant boons” that’s constant.
In Campbell’s observation, these stories have a cultural function - they’re usually about resolving psychological tensions and navigating liminal spaces. Just using it as an outline to fill in the blanks without understanding why and how those scenes function is going to fall flat every time.
But at the same time a lot of the time people in real life don't show nearly all of what is going on with them.
In that case "tell" either gets contrived - you end up with convoluted attempts at externalizing thoughts in way that bears no relation to how the character would act in real life, or you ignore the story. The former often leads to lots of monologues or contrived props to make the character show you things in ways that makes no sense. In the right setting that can work, but often it is just jarring to e.g. have a character talk out loud to themselves or otherwise act out things they'd be more likely to just have thought about.
This seems to be why she is bringing up abuse, for example. An abuse victim writing about their experience can certainly "show" the abuse, but how do they show how it made them feel and what it made them think about, when they've often worked hard to keep a mask and not show the world how they were affected?
It's good advice to show, not tell, on the basis that most people who haven't written much tell way too much and show too little. The problem is that it is then sometimes overdone. It doesn't always makes sense to show instead of telling. Either because showing becomes contrived, or for example because showing commands attention, and sometimes you want to tell to avoid drawing attention away from the main thrust of a scene or a work to some detail necessary to understand what is going on, but not important enough to show.