I was going to write a big essay post on this, but pretty much everything I was going to say has been covered allready.
your forgetting aswel the years of training that most professional photographers go through, at their own cost (in most cases) I'm in my 5th year studying the subject, (doing my BA) and it's cost me thousands... my Degree cost me around £3000 just in fees...
and my BA is costing me another £1200, This money has to be recouped somewhere...
The cost to set up even a small business shooting schools etc will go into the thousands, there is so much kit and equipment you have to buy,
Camera body, lenses, transmitters/sync leads, studio lights, backdrops, bags and cases, batteries, photographic media (cards/film etc)
then you have to factor in transportation costs, and if your working with kids your going to have to have them police checks done,
as for output, not all photographers have in house printing... the "worked" images are often sent off to a lab for printing, which adds to the cost. then theres the admin side of things. I've worked in a studio that specialized in social and wedding photography, and the amount of time I spent trawling through orders cutting prints, mounting them and prepping them for sale could have been a full time job. So if the photographer hasn't got another assistant working on that he/she is using time they could be producing more work outputting previous work.
It's a hard job, it's not just "turn up set up some lights and press a button" people have to remember that it is a real job that requires real skill. And the people doing it have to make enough money from it to eat and pay the bills just like the rest of you!
This isn't a rant, btw...