The US police doesn't even care if people are overtly filming them killing people without cause, they still get away with it.
How would a "hidden" camera change this?
Also, it is fairly easy to see the camera lenses on smart glasses, they could easily find a way to knock the glasses off your face and step on them to look like a plausible accident.
You take them to court, the police department pays, best case, the police is transferred to another district.
It is far better to have a dashcam with a fisheye lens in your car, it is easily overlooked and and has a large FOV, while also picking up sound.