Why do insurance companies have so much control?

I have a high school basketball player that suffered a knee injury a couple of weeks ago.  Because of all the budget cuts in the schools, I do not cover basketball games for my schools on a regular basis so unfortunately I was not at the game that she was injured in. 

Her coach called me first thing Saturday morning explaining that his player was in a lot of pain and was asking what options he had.  I gave him the standard "RICE" treatment to get her through the weekend, and got her in to see our Physician's Assistant Monday afternoon.  I don't go to the schools until Tuesday, so I was not able to see her prior to her appointment. 

So the PA looks at her knee and decides one of two possibilities has happened.  She has either torn her meniscus or suffered a sprained MCL.  We ruled out an ACL so the next step that was mutually agreed upon was to have an MRI preformed to see exactly what was going on. 

The office calls the girls' insurance company to get the MRI approved prior to the testing being done, and the insurance company denies the request for an MRI due to there being "insufficient evidence" that an MRI is necessary.  They don't believe that an MRI can be ordered following one visit with the doctor.

The girl was then given the option to have a brace placed on her knee and given some rehabilitation exercises to build up strength in the muscles around her knee.  She tried to play, but has little success.  She falls regularly during games and then takes herself out of the games.  Tests were preformed in the clinic showing her legs were strong enough to not have to worry about further injury and she was able to pass a functional jumping test, so there is no reason medically that we should hold her out of activity. 

Today she went in for a re-check on her knee and pending approval from the insurance company, has an MRI scheduled tomorrow.  I just can't believe how insurance companies (who have no medical background) have so much power that the can say what is and what isn't "ok" to preform on patients.

GRRR.....