You raise a valid point that digital signatures and HTTPS alone cannot guarantee the authenticity of a recording. However, modern smartphones and other mobile devices have the capability to provide stronger assurances about the originality of recordings through the use of tamper-proof secure hardware.

Many high-end smartphones, such as iPhones and some Android devices, incorporate secure enclaves or trusted execution environments (TEEs). These are isolated, tamper-resistant hardware components that can securely store and process sensitive data. When a recording is made on such a device, the secure hardware can associate the recording with additional metadata, including the specific date, time, GPS coordinates, and user account information. This metadata is cryptographically bound to the recording itself.

Furthermore, the device can digitally sign the recording and its associated metadata using a unique key stored within the secure hardware. This digital signature serves as a testament to the recording's originality. Companies like Apple or Google, who manage the secure hardware and signing keys, can then vouch for the authenticity of the recording.

While this approach doesn't completely eliminate the possibility of fake recordings, it significantly raises the bar for creating convincing forgeries. Modifying the recording or its metadata would invalidate the digital signature, making it evident that tampering has occurred.

Of course, as you mentioned, trust in the entity verifying the signatures (e.g., Apple or Google) is still required. However, this trust is based on their reputation and the security measures they employ, rather than on the content of the recording itself.