If landslide isn’t covered, why are premiums higher in a “landslide susceptible” area?

I'm moving to an area with a history of landslides (CO) for the first time, and working on purchasing a home. We quickly learned about the local landslide areas, and found a Colorado Geological Survey map with some good delineation of what is and is not a landslide susceptible area.

I quickly found looking at houses that stuff in the the most active landslide areas was either uninsurable or ~50% higher than similar sq ft outside the area. Made sense, there was more risk there.

However, I recently found out that landslide isn't covered under homeowners insurance. Crazily enough, it's hard to get any form of insurance for landslide.

My question is, if landslide isn't excluded, why is it very obviously influencing premiums? This is across multiple insurers and areas in the region. It would seem to my uneducated eye that if the landslide area is excluded from coverage, then it shouldn't effect the premium at all.

What am I missing?