I'd agree with you here, there is a tendency to overprescribe, and I think depression is showing a natural response to unhealthy and difficult condition (perceived or actual). Are they "sick"? well technically yes, just like one could have a flu and can't work. I think a better analogy would be injury, it is as if the mind is injured, kind like a broken leg that you can't walk on.
Psychiatrist and family member tend to fear relapses, and typically the effort required to enhance the situation is tremendous, and some situations are simply not fixable, they need to be accepted, time need to pass for healing, and attention need to be shifted elsewhere. The person would certainly lose some confidence in their own ability to withstand future pressures and tend to fear relapses as well, and yes there are financial incentives to sell pills and pitch as an easy fix. Thus, there is a risk of being dependant on the pills.
However, a good treatment plan is a mix of medicine and some form of talk/behavioural therapy. The medicine is designed to be temporary but might be necessary fix (unless there is a real hardware issue which I think is a rarity), and is usually combined with CTB and other form of talk/behavioural therapy aiming to strengthen healthy coping skills, eliminate damaging thoughts, change perception and take some actions. Do some people need medicine for lifetime? I don't know personally, but I've a feeling it is being overprescribed and it might cause more harm than good if taking for a long time. I mean, who knows what it does to the brain reward system if used long-term? I don't think it is well understood.
Ideally, people are given the time/care to heal on their own, around 3 to 6 months at least for severe depression and usually the person emerges at the other end have different perspective/interests in life. But the problem is the economical system is setup for constant productivity and 6 months of downtime for many of us is simply not an option.