By this logic, why have laws at all?

Laws are needed for a civilized society. but civilization is a safe area we've created for ourselves in a dangerous jungle. When we step outside of our civilization we're in a lawless place and we're just surviving based on or abilities and judgement. There's no legal way to eliminate the jungle, it will always be there. But that doesn't mean we shouldn't bother to have nice things when living in our civilized society.

A lot of these hypotheticals and real world scenarios are just people going out from civilized behaviour to the edge of the jungle. Whether it's a King making commands or a President ignoring the court, these are things that shouldn't be done based on the norms and laws of our civilization. So we're in jungle rules, we have to figure out how to deal with the problem based on just our abilities and out judgement.

I see your point that “if we all agree he has no power, any exercise will clearly be a problem” … except the monarchy is in constant contact with the governor general. You won’t know why the GG makes her choices.

Parliament would know. Their job is to represent the will of the people. If the GG or King weren't doing as they were told by Parliament, the PM has able opportunity to say to the country "that's not what I wanted them to say."

Or consider this situation: https://donshafer1.substack.com/p/the-day-37-british-columbia-mlas . Imagine the King has business interests in BC and would benefit from this financially. He calls the GG, who calls the LG of BC to say “get this moving.” If the LG (or GG) went public, she’d lose her job. So she’d quietly do it.

There were 50 MLAs that voted against that. How would the LG be able to do this quietly without the 50 people that voted against it knowing about it? When legislation gets royal assent, it's done so publicly. Someone reads it out in Parliament and the Governor gives it a nod. It's all a formality really, but who would be the person in parliament reading out legislation that didn't pass to a Governor in the first place? You'd have to have the Parliament's Clerks in on the scheme and not have them leak it to the the representatives, And they would be fired if caught doing any of this. Laws obviously have to be published so people like your self can use them in court. How would a GG, LG, or the King himself be able to do something without the elected representatives who voted against it knowing about it?

There's a lot of process and ceremony involved in this: https://www.ourcommons.ca/procedure/our-procedure/LegislativeProcess/c_g_legislativeprocess-e.html How would you slip some secret laws through all of that process?

And I think you have it backwards. If something like this were to happen, there would be no more King. Even if the King were to force laws to come into being somehow (don't know how it would happen, so it wouldn't be the normal process, therefore very obvious) people would know and either the King would have to undo the action and abdicate or we'd just cease to be a monarchy. We'd be in the jungle and we'd be acting on our abilities and judgement.