Aadhar is "identity", it is not a "card" of any kind though Indians have inherent love for collecting various cards for fun. I have my driving license, PAN, aapar, kisan and state government health insurance cards, labor department id card. I have few more in some drawer.

Once a person gets aadhar, it acts pretty much same as OAuth. You go to a hotel to get a room, Hotel by law is required to verify that your name and face match. You give your aadhar card to them which they scan on their computer and verify that your name matches your face. Because they are a hotel they have right to only verify that.

This is much more privacy preserving than what supreme court did. Because of Supreme Court, hotels no long bother to implement this and instead demand your passport and other identification, scan it and leave it in their system forever. They also are known to sell this data to other from time to time.

The technical idea behind was aadhar was similar to UPI. Government runs the core infra with basic APIs but private companies build apps on top of it. For example, say GPay builds aadhar interface where when you walk into a hotel to reserve a room, Gpay automatically generates a new aadhar number with permissions only to show your name, photo and age. Hotel system verifies that and stores a receipt. If in future government is investigating who stayed in which room, law enforcement can convert these receipts to identification.

This was a better model which would have unlocked a lot of potential. The government failed to argue the case correctly and supreme court acted more like an activist court.

I do think both Government and Supreme Court failed to show the correct user journey here.