You have them.
> then that person has, as you say, no plausible deniability at that point, do they not?
No, they have plausible deniability if they use the common device.
> Are we talking about legal accountability
Social and legal.
> What do the glasses enable that any other video camera does not?
The glasses enable the wearer to say, "Oh sorry I didn't know they were recording." Or "They weren't recording, they're just glasses." Using a handheld VHS video camera from 1992, in 1992, would cause you to get arrested in a locker room because there is no plausible deniability. The recorder definitely chose to use it there in violation of social norms so off to jail they go.
> argument.. would have to be applied universally
Yup.
> how would it be if the manufacturers put a big, red light on the front of the glasses, that would automatically turn on when the glasses are recording
Someone else in this thread suggested that the entire rim of the glasses light up in a plainly visible and obvious fashion, including in broad daylight. That would make it acceptable because then you could tell the person, "Hey your glasses are on. They should not be on." And then the person can say "oops" and we all go on with our lives.
> You're looking for a way to prosecute unethical individuals...?
Prosecution is not strictly necessary; social effects would likely be good enough just like they are in most other contexts. Especially because many of the bad uses of these glasses will simply be mistakes. I can give you an example. I was changing in a men's locker room. You may be completely naked. There are showers and whatnot. Someone had a tripod set up with a phone attached and an LED light to take video of himself in the large mirror they have there. He surely didn't know that he was doing anything wrong. But he was. He could be told not to do that because we all could tell it was happening. With glasses, we can't.
This is an example of a problem that the glasses bring but the fact that I have typed it should not imply that it is my or anyone else's only concern. There are others.
> at least until large swaths of society accept the existence of video recording glasses like we already do with smartphones
There is no guarantee that this will happen. Open display of a firearm will get you put in a police car in many places despite owning it being a right enshrined in the constitution. You may drive a car but not anywhere you want. You may use firecrackers sometimes but not anywhere you want. You may own a cell phone but not possess it wherever you want. You may buy a backscatter x-ray machine but you may not use it wherever you want. Examples abound. You will almost definitely be able to buy Meta glasses in the future but there is no long-term guarantee that you may use them in public.