Retouching varies from image to image and from photographer to photographer. Part of what you're paying for in photographic skill is in the retouching style. It is closely associated with the photography brand and style of editing.
In the below 2 images are exact duplicates with exception to the photo editing style and technique. On the left you will see the unedited photo. On the right is a photo that has had a a moderate amount of editing done. Can you easily see the difference?
Hopefully, now you see the advantage of not only paying for additional retouching but also why never to ask for raw or unprocessed images.