It’s not unusual for shops to demand a telephone number during even small purchases, and your number will be spammed with SMS ads shortly thereafter. Also email spam if they somehow get your email.
Chat archives (possibly backups?) of people under investigation have been leaked to the media with no consequence to the leaker.
Essentially it’s an extreme “laissez-faire” environment, one almost out of a textbook example of what happens in the absence of any regulation whatsoever.
The above doesn’t have anything to do with Facebook or WhatsApp (except tangentially), it’s just to note that privacy legislation would be a very helpful quality of life improvement for many Indians.
Perhaps someone on HN who knows more about this can share why the efforts to have privacy legislation in India have so far been unsuccessful.