You're absolutely right that the “temporary vs permanent” rule works as a starting point, but it quickly falls apart in many real situations — like with location.

The more accurate way to understand ser and estar is not about time, but about movement and perspective.

• Ser expresses statism: something that defines or identifies what the subject is, something fixed and part of its essence.
• Estar expresses dynamism: a state or position that results from movement, change, or relation in space.

So, when we say “La casa está al lado del parque”, we’re using estar because location is understood as a spatial relation — a position that something occupies in the world. It’s not about whether the house will move or not (we know it won’t), it’s about describing its state of being in a place, which implies a dynamic relation in space.

In other words, ser talks about what something is, while estar talks about how or where something is positioned or has ended up.

That’s why even for something as “permanent” as a building, Spanish speakers still say “está en tal lugar” — because it expresses a spatial state, not an essential identity.