What if information can't be revoked on systems outside your control? That's the reality, however many secret handshakes you do, blockchain, etc, eventually some person or process knows something and can do something with it (e.g. copy it).
You could pull a gmail and say, there is no human in the loop, it's just a process of personal data ingestion and ads come out the other end. That might be more comforting if it was open source, but even open systems have things can be hidden in obscure technical details.
The truth is, we are all human, including our leaders. Your average human is weak and susceptible to trading a vast privilege like having control of everyone's whereabouts for favors (e.g. money, position, control, sex, etc...).
I'm a sucker for an open source process (e.g. robot) that would look at the data and tell us who needs to be quarantined, but again, you still have human technical people, with all their failings, controlling the system (e.g. source code). How much do you trust the open source process is a matter open for debate.
The simple example would be "I'd like to send indigochill a gift", which would send a request to your API (with some notification for you to approve or deny receiving said package) and return an id that could be written or printed on an envelope. That id is unique and the mail service would scan the id and the package would be routed. And the mail carrier would scan the id and get an actual address (or a blip on their map of the block or something). Nobody along the way has learned your address or name or anything - nor do they know my address, which is just another unique id.
There are some very interesting implications in that data can become stale so quickly. If you approved of receiving the package but were out of town for the week, the package could be routed directly to you without any interaction whatsoever. Nobody along the way would know the difference between your home or your hotel room.
The same could easily be done for lots of personal data. Phone numbers, email addresses, etc. All your shopping history could be stored on your own private data store and the local grocery stores would send out a mailer "Address this mailer to all people in the neighborhood who have purchased discounted burgers in the past month". The store doesn't know who is getting the flyer, but the people who would be likely to use a coupon for buying burgers would get a notification and likely go buy some burgers on sale - or reject the notification and not be bothered - to the savings of the store and the recipient.
Social Media could still exist with this sort of thing but the services would be querying engines rather than the creepy data warehouses that they've become.
This of course gets significantly harder with the queries this article is about, but the idea is the same. Instead of "give me everyone's location for the past month", the request would be "give me the anonymized ids of people who have been to x locations for x amount of time within x amount of space between one another". The response would provide data that could be used for the purpose in question, but the underlying data remains private.
I've been pondering this idea on random occasion for about 15 years, but I don't care enough about it to make it my life's work. But I sure would like to live in a world with that level of data ownership and privacy.
In the meantime, sounds like most likely outcome is the government hits CTRL C, CTRL V on Facebook/google’s user database and starts a China/Tencent style SQL dB on every American.
Or even more likely, this already exists and now the government can start using it more openly.
Of course none of this stops the person with temporary access from making a copy to save forever. I doubt that problem has a technical solution but would love to be proved wrong.
This is probably pure fantasy, but if there was any way this scenario would be possible, I think it would go a long way to assuaging people's concerns. As it is, we know data can be copied and distributed without permission. That's kind of been the underlying problem of spies throughout the history of the world.
I think this concept is where Stephenson was going with Snow Crash, but his scenario for this seemed like fantasy as well to me.