If they were not full of BS, they would use the existing technology that supports privacy and free speech, but protecting kids is not the reason for the law.
The best current anonymous age verification systems focus on privacy-preserving technologies like zero-knowledge proofs (ZKPs), selective disclosure credentials, reusable anonymous tokens, and double-blind architectures. These allow a service (e.g., a social media platform) to receive only a "yes, 18 " confirmation—or a unique, non-linkable token—without collecting, storing, or linking to names, exact birthdates, full IDs, or other personal data.