If I had my 'druthers, there would be a kind of physical vending machine installed at local city hall or whatever, which leverages physical controls and (dis-)economies of scale.
The trusted machine would test your ID (or sometimes accept cash) and dispense single-use tokens to help prove stuff. For example, to prove (A) you are a Real Human, or (B) Real and Over Age X, or (C) you Donated $Y On Some Charity To Show Skin In The Game.
That ATM-esque platform would be open-source and audited to try to limit what data the government could collect, using the same TPM that would make it secure in other ways. For example, perhaps it only exposes the sum total of times each ID was used at machine, but for the previous month only.
The black-market in resold tokens would be impaired (not wholly prevented, that's impossible) by factors like:
1. The difficulty of scaling the physical portion of the work of acquiring the tokens.
2. Suspicion, if someone is using the machine dozens of times per month—who needs that many social-media signups or whatever?
3. There's no way to test if a token has already been used, except to spend it. By making reseller fraud easy, it makes the black-market harder, unless a seller also creates a durable (investigate-able) reputation. I suppose people could watch the vending-machine being used, but that adds another hard-to-scale physical requirement.
> 2. Suspicion, if someone is using the machine dozens of times per month—who needs that many social-media signups or whatever?
Anyone who visits pornhub and doesn't want to open an account?
Yeah, introducing real world friction is seemingly one of the only ways of actually solving the problems of frictionless digital systems (apart from computational disenfranchisement, of course).
It might be a better idea to frame your idea in terms of online interactive proofs rather than offline bearer tokens. It's of course a lot less private/convenient to have to bring a phone or other cell-modem enabled device to the vending machine, especially for the average person who won't exercise good digital hygiene. Still, some sort of high-latency challenge-proof protocol is likely the way to go, because bearer tokens still seem too frictionless.
For example (3) could be mitigated with an intermediary marketplace that facilitated transactions with escrow. If tokens were worth say $2, then even just getting 10 at a time to sell could be worth it for the right kind of person. And personally I'd just get 10 tokens myself simply to avoid having to go back to the machine as much. In fact the optimal strategy for regular power users might be to get as many tokens as you think you might need to use (even if you have to pay for them), and then when they near expiration time you sell them to recoup your time/cost/whatever.
My concern with some "bring your phone and use it immediately" scheme is that someone could pierce the privacy by looking at a correlation between the time an account was mode or a pattern of network-traffic occurred, versus the time someone was using/near the vending machine.
Adding large and unpredictable amounts of latency makes that kind of correlation weaker and hopefully impractical.