Laws like COPPA in the US, the UK Age Appropriate Design Code, and EU GDPR carry statutory penalties of over $50,000 per violation if minor data or chat sessions are mishandled without explicit parental consent.
For an enterprise and developer-focused company like Anthropic, minors contribute negligible revenue while representing 90% of the catastrophic regulatory risk. From a pure cost-benefit perspective, outsourcing age verification to an external vendor and shutting down the under-18 demographic is simply the cheapest way to wipe that liability off their books.