As to why its such a ridiculous situation in India - as per my limited backpacker's experience marihuana is a sacred plant, used for thousands of years to celebrate god Shiva, one of main deities in Hindu pantheon. Seeing a sadhu (holy man) to smoke chillum is as regular sight as birds flying in the sky, I was once even given such a chillum within bigger group of sadhus on Ganges bank (I think in Haridwar).
Its like India becoming world dominating power and starts forcing every single christian country on the world to ban alcohol or using wine in religious ceremonies. And they actually implemented it for solid 6 decades so far, via United nations being a slave to US (and when its not, US presidents are quoted about kicking them out or simply ignoring its existence).