Personally, I haven't found this to be the case. It seems like the opposite tends to be true from what I've seen: doctors are quick to prescribe drugs for mental illness and depression, whereas talk therapy is cast off as "too expensive" or "not useful". Insurance companies won't pay for more than a select amount of therapy sessions, but they'll happily shell out coverage for any number of psychiatric drugs.
I think therapy would likely be MORE effective for a lot of people suffering from mental illness than simply shoving drugs in their mouths that merely mask the symptoms. We get told that mental illness and depression are simple "chemical imbalances" in the brain that can be corrected by drugs...but I don't believe it.
Sure, in some situations that may be the case, but I think that for the vast majority of people, mental illness (particularly depression) is caused by a combination of internal and external factors, such as childhood trauma, bullying, poor coping skills due to inadequate parenting, environmental stressors, dissatisfaction to due ill-suited jobs or living situations, etc.
For these people, I really don't see how putting them on drugs really helps to improve their situation in any long-lasting way. It merely numbs the symptoms. For some people, that numbing may be enough to keep them feeling somewhat level-headed in dissatisfying life circumstances.
For others, though, I believe long-term therapy that teaches them coping skills and how to sit with and understand their pain- as opposed to just numbing it with drugs- would garner much more substantial gains in terms of healing and recovery.
The fact of the matter is that our pain has meaning. It's trying to tell us something, and what that something is may not be totally clear at first until we learn to sit with it long enough to recognize what it's trying to tell us and where it originates. Pain isn't just some meaningless burden we need to escape as quickly as possible.
That's what the drugs do, imo. They provide an "escape" without lending to any kind of true, long-term growth or change. For some, that's all they want. But, I think a lot of us out here have been tricked into believing that mental illness is just a "chemical imbalance" that we can rectify with drugs rather than, in many cases, a legitimate mental and psychological response to pain and suffering + inadequate coping skills to deal with that pain. I don't buy it.