It’s implied that no one should be taking photos of youth without parental permission.
Part A of the AHMR contains a section titled Informed Consent, Release Agreement, and Authorization and at the end of that section is a space labeled List participant restrictions, if any: That is where a parent would list a restriction of photos and/or video if they desire that restriction be in writing.
The form is not about the event or about any level in Scouting (district, council, etc) but rather the form applies to the youth, no matter what activity they are involved in. It also applies to adults who also must have an AHMR on file.
You’ll not locate any other document on scouting.org that is intended to be a record of a parent denying photos/video of their child. You will find a “Publicity Waiver and Release” of which the specific intent is to document a parent’s permission.
Why? Safety of the youth is our primary job and that safety extends to visual media.
No one should be taking photos of anyone else’s child. No one should be posting photos of any children on the internet without a parent’s expressed permission.