Maybe in your favorite resorts, some ski pistes are maintained but not groomed. However, they are part of the 'official' and securized piste network.

In openstreetmap, they are called piste:type=dowhnill + piste:grooming=backcountry.

Now, in OpenSnowMap.org, this is dashed lines, colored by difficulty. What you see on the left (the orange dots) is something different, they are piste:type=skitour.

backcountry.png

A very good suggestion from user pkm. Thanks Peter !