But this is a religious custom, as noted by your usage of the word Hindus. Muslims dont bath in the Ganges, so I wonder if you are gettting confused between religion & culture.
But there are Indians who continue to do it even if they're more or less just 'cultural Hindus' - so its a bit like hotel california, you may check out but you never leave.
I agree that cultures around the world have got a long way to go; misogeny, homophibia, racism to name but a few.
But they are all evolving and adapting with education and communication. I think religion is a much bigger problem.
Religion is inflexible by its very nature, and I would argue was an designed to counteract the versatility of culture, its non-uniformity and its adaptability to change, that the 'chosen few' did not like.
But is the inflexibility linked to the inflexibility of the culture; during the first 200 years of the Muslim community there was flexibility, different competing philosophies, interpretations, traditions and so on. The problem comes when religion starts to solidify into rigidity resulting in the dialogue ending and people just simply rolling along on the fumes of past scholars and clerics.
Compare that to Christianity that has gone through reforms of all sorts; there are Christian churches from all across the spectrum; from ultra conservative at one such as the 'Southern Baptist Convention' end to the MCC which is a gay-positive church. Judaism where you have ultra-orthodox at one end with stringent abiding to the 613 religious rules to liberal judaism at the other end of the spectrum - and the irony being that the reform judaism being older than the ultra-orthodox movements.
For me I find blaming Religion as a bit of a cop out because there are those who have left religion and their views are just now being hidden under a new ora of legitimacy - the new atheist who legitimises his hatred of gays by using psuedo-scientific language in lieu of using the religious language he would have used a couple of years ago. In the case of Pakistan the identity is defined on the basis of 'not being India', Islam is exaggerated to the extreme with any questioning of Islam being quashed because it threatens to destabilise the identity, so with that sort of environment is there any surprise that Islam has become so rigid given that Pakistanis are so dependent upon it to provide an identity for something that really cannot be legitimised on secular grounds.
Topic: The Inconvenient Truth About Islam From an Ex-Muslim Woman