If so, then that basically means the government knows who you are shopping with. That's all sorts of overreach. Unless it's for tax purposes, I don't see why the government needs to know who you choose to buy from. What if someone buys from a controversial source - does the Indian government really need to know what sort of porn companies someone purchases from?
And if it's just an ID, then how does Amazon know that someone hasn't stolen the ID and just provided it for identity fraud? Or do you also have to provide some sort of biometric verifier also? Either case sounds pretty fraught with difficulty.
In Australia, everyone has a Tax File Number. It's not that well known, but retailers who ask for the TFN are breaking the law and will be fined a huge amount of money.