I have many concerns with this kind of funding model, but I don't think the measurement problem is so serious. Performance incentives in education typically reward improvement of the student cohort relative to how it was performing the previous year, or even use value-added models that use multiple past years to predict the student trajectory.
I love cities that embrace street food. My home (New York City) is well-regarded for street food, but I found it that it's nothing in comparison to Mexico City where a vendor seems to dot every single street corner.
With our density, New York could have a much richer street foods scene if the permitting and regulations allowed it.
I am an airbnb host, and exclusively rent out my own apartment on the handful of weeks per year that I'm traveling.
If airbnb was banned, my apartment would be vacant during that time. This would push tourists into hotels, driving up the cost of a hotel room, and furthering the affordability crisis since developers would see more upside in hotels rather than residential development.
There are still crypto projects whose primary focus is privacy (eg monero). But unsurprisingly, it's difficult to spend that money without going through a KYC process.
I think the "dream" of truly private transactions was always unrealistic. Governments have many tools at their disposal to get what they want.
Even cash is only so private. In the USA cash purchases over $10,000 require a report to the IRS.