Here's the actual paper of the technology (Prio) that it's based on.
Some problems stand out:
- It requires that the organisations (Mozilla and ISRG) not collude to decrypt the secret share (probably reasonable)
- The paper suggests registering end users to protect against Sybil attacks.
- The scheme requires the organisations to correctly withhold results from advertisers until there are sufficient results.
I'm not overly familiar with the tech stack but I'd be concerned about browsers using a persistent UUID to send impressions to Mozilla's API.
The biggest elephant in the room is that seemingly nobody wants the damn thing. It offers nothing to users, except maybe a good feeling inside that they're supporting AdTech. It offers AdTech less than the current deal where they can collect obscene amounts of personal information for targeted advertising.
I sold my car last year and barely gave it a secomd thought (I still have access to a car on weekends). Money, environment and space-saving were all factors.
I don't think government should be in the business of subsidising driving (which is currently the case in multiple ways). Instead that money should be used to make public and active transport safe, convenient and reliable.