I read this wonderful piece about why professional photographers charge so much money.
In essence, the time spent shooting is less than a third of the time it takes to produce the images and get them to the client. From the time it takes to organize the shoot, get everyone on board, set up the lights and camera, prep the client, shoot, clean up the shoot, import the photos, select and cull for the best, edit the photos, deliver the photos to the client, and follow up.
Then there is the whole cost of doing business. This ranges from the cost of the studio to the camera and lenses. The often overlooked insurance and business maintenance costs.
The breakdown is rather interesting in detail. I highly recommend reading the article.