Here's how a typical earthfill carrying a roadway joins a typical bridge
Parts of the earthfill slopes are greenish - that's grass - and parts are whitish - that's concrete.
The earthfill slope is fully covered in concrete where it joins the bridge but the rest of the earthfill is only partially (lower part only) covered in concrete, the rest of the slope is grass-covered.
This photo is of a 20+ meters high earthfill and lower earthfills' slopes are usually not covered in concrete at all except where they join bridges - the join is usually fully covered regardless of how high the earthfill is.
What's so special in that part where the earthfill joins a bridge that this part is fully covered in concrete while the rest of the earthfill is either partially covered or not covered at all?