There are so many great blog posts about this. The big ahhh haaaa moment for me was realizing that the chain stores main reason to even have a photo studio is NOT to photograph, it is to get the customer INTO the store to buy more clothing, appliances, shoes, whatever....
Think about it. Where are the photo studios located in most stores? In the kids clothing section or at a location way into the depths of the store, so you have to pass every other section in order to even get to your appointment. Even walmart, yes, the studio might be at the front of the store, but you are IN the store.... most likely you are going to go get some milk or bread after your session..........
When you hire a custom photographer, they are there for the client, from start to finish.
Another thing is they hire based on sales experience, not photography knowledge. The cameras are basically set on auto and configured to the studio lighting, can never be changed. I have a friend that works at Sears every holiday season as a photographer... She doesn't even know what shutter speed is. She is a people person and can make good sales, so they hire her, to SELL you pictures of your loved ones.
Also, google newborn hospital photographer. Several positions will come up clearly proving this, showing sales experience a MUST, photography experience not needed.... wow really? amazing!