The NHS give a damn, but it's a Sisyphean task trying to tackle mental health in the UK. Our living standards and general wellbeing are quite low compared to other European nations - we are some of the most overworked, stressed, and pessimistic people out of the whole bunch. Look at other nations with similar living standards and you will see - especially in cultures where it is not so taboo - suicides rates rise dramatically (e.g. Japan, honour-bound society).
The fact is that mental health is probably the biggest single health problem for the Western world. The single biggest unacknowledged problem, I guess you could say. And it is extremely expensive to properly care for - just as expensive in the long-term as a person suffering a serious physical illness. A GP, quite simply, does not have the funding or the time to refer every single one of their depressed or anxious patients to a specialist for therapy. Therapy is expensive and, furthermore, underfunded. The result? Most GP's only have one real path of treatment open to them: heavily-subsidised medication. Hence everyone is on pills but hardly anyone is properly getting the treatment and psychological help they need - because it's so bloody expensive.