We could consider making duplication default, or even having an option where you can decide your default. But doubling a command like that to save you from clicking on a checkbox will never happen.

But it already happens!
With duplicate, for example, until Capture is closed.
It happens when we import an object from the library and fix its height for future insertions.
If there's a difficulty in software programming, I'm not an expert on that.
It's not a matter of saving a click, it's a matter of consistency.

Take a look...

Always trying to collaborate and avoid creating controversy.
I won't insist any further after this.

I don't think it's a matter of controversy as much as misunderstandings in terminology.

By "default behaviour" I mean what happens the first time you use a command, in a new project. For the mirror command, the default of the duplication option is to be off.

Once a command has been used, settings are remembered, so that option dialogs open as you left them last time.

I understand and fully accept that.

But that's exactly what I was asking for the zero axis position.

With a default value of zero from then on, the behavior would no longer be to zero out the position to duplicate it.

It would be a default behavior marked in a box until we close Capture or unmak the box, like Duplicate.

So you want to have a separate Mirroring command that always duplicates and you want it to ignore the position of the rotation anchor and instead always mirror around origo?

If this way is simpler, yessss