They chose not to make this feature opt-in because they know that nobody in their right mind would opt into it
Nobody would opt into it because like your OP said, there’s an astroturfing campaign to make sure that people completely misunderstand what the feature is and what it does.
When everyone around you lies to you and tells you that seatbelts are “unsafe” and then the Feds come in and say “no they’re not”, you’re still gonna believe everyone around you even if they’re patently false. Hence forcing it so people see there isn’t a problem.
They already have your photo for your passport or license and they don’t need permission to take video or photos in an airport at all.