People in the west walk with cameras in their hands all day - both in public and in private. I doubt it gives anyone pause.
Unless someone is actively pointing their phone at you, you can reasonably assume you're not being filmed.
this thing, on the other hand, is supposed to be on all the time. So having your head pointed in someone's general direction is going to be interpreted as "actively filming that person".
This could easily lead to getting punched in the face.