Our actions in everyday life are progressions of narratives, one action leading to another, progressing however they can.
The information that determines our actions is hugely grounded in constant physical constraints that surround us.
When asleep, we are still to an extent mentally active, and in fact acting in a way that clears up our minds
To clear something from one's mind is to clear the backed up stack of planned actions and close the narrative. When you finish a task you free up capacity.
When dreaming, however, the physical grounding disappears. What we retain is the invariant structure, unmoored from physical constraints we otherwise rely on.
As a result, we carry out something effectively isomorphic to what it would be in the waking world, thus the existence of symbolism.
It's nothing supernatural, it's just a question of what we store in memory and how its manifestation is context dependent.
This may *incidentally* bypass repression because repression comes from habits, habits that we may not have control over when asleep. But there's no active conspiracy by our "subconscious".
Whether that's a good thing: fuck if I know.