> the GDPR which never mentions either aircraft or cars

ICO's guide to the UK GDPR does have a specific example of cars being identifiable[1] - "A vehicle’s registration number can be linked to other information held about the registration (eg by the DVLA) to indirectly identify the owner of that vehicle." Nothing about planes though.

[2] covers car registrations and explicitly discounts company owned vehicles from being PII - "The registration plates of commercial vehicles are not personal data of an individual as the vehicle is owned by an organisation."

All of Ol' Muskie's jets are owned by Falcon Landing LLC, a shell company.

[1] https://ico.org.uk/for-organisations/guide-to-data-protectio...

[2] https://sapphireconsulting.co.uk/is-a-car-registration-plate...