[webmobdev]

It's rare. The answer would then depend, I guess, on how comfortable are you in allowing mentally troubled people to opt-in in for suicide.

[hotpotamus]

Look at the success rate of SSRIs and other common antidepressants and you might find it's far from rare. You say yourself that the depression is near universal amongst the old people you know, have any of them had successful treatment?

[webmobdev]

No, unfortunately psychological treatment are neither easily available or popular in India. There is also a cultural aversion in the previous generation to availing such treatment. (On SSRIs note that the medical community is increasingly of the opinion that SSRIs don't help with depression in the long-term and may even be responsible for suicidal tendencies in those who never even had it in the first place. Cognitive Therapy is now the gold standard for the treatment of depression.)