Yup, that's pretty much the question that has bedeviled all blockchain "innovation" since day one. Cryptocurrency still works (for some value of works) because

Yup, that's pretty much the question that has bedeviled all blockchain "innovation" since day one. Cryptocurrency still works (for some value of works) because it's self-contained, but as soon as you need to track anything in the real world you run into the oracle problem: how can you trust that what the blockchain says about the world is correct? (Spoiler, you can't.)