What you are proposing is too sweeping, it is not just privacy that suffers. Making a single ID (whose attributes can't be changed) an entire identity of a person is a very risky one. This makes it a single point of failure and in cases like an ID theft, misuse the affected person suffers gravely, and onus will be on them to prove who they are, a Kafkaesque nightmare it would be.
There are several countries which use a single ID for all government interfacing. For that matter, Aadhaar is almost there already. I am not suggesting that private companies should use it, or should be allowed to use it. But a single ID will limit babudom arbitrariness a bit.
> whose attributes can't be changed
Many IDs (outside India) have similar issues, options to change attributes, and various redressal mechanisms.
I don't know of how digital IDs are used etc. in other countries and how ubiquitous there usage is. (One ID I'm aware of is social security numbers (SSN) is U.S, but that is considered as PII data and usually companies take steps to protect/mask them). But citing that this is how it is done elsewhere is just an appeal to tradition/common practice and not necessarily addresses the points I had made.
