Why do we have to "fail" to get somewhere with insurance companies?

I have a wellness plan in place, but even the best wellness plan doesn't keep me from strong feelings about suicide, until recently.  Recently I began a new drug via samples from my APRN.  After months of taking it, we found out people are being told that they have to "fail" three antidepressants before they can take it.  So, I was really worried about this because after months of being free of suicidal thoughts, I might have to lose all this wellness.  So, I called the insurance company.  They tell me its on the formulary, just send in my prescription.  So I do and I wait.  I even get an email that its on the way, but something is fishy about how long its taking so I call.  I find out that they have to have my doctor fill out a form before they will give me the drug she prescribed that is on their formulary!  Can you believe this?  A good friend of mine just went into the world of disability because she can't find the right concoction for her condition.   Another friend had to "fail" six drugs to get the treatment she wanted.  Then I find something that works and I have to prove something to get what my doctor says I need and the formulary covers?  No wonder people complain about the complexities of the behavioral health system.  We can't even just get drugs that work, when we need them. I'm waiting on the answer, but I shouldn't be waiting.  The healthcare system should consider quality of life, people being well enough to pay taxes, and never making people "fail" to be well.