You've run into a site you view on chrome/firefox/safari accessing your camera without granting access a few times now?
Can you give us an example of a site that does this so we can reproduce? Or could you retract your statement and clarify that you did grant camera permissions for that site previously?
Otherwise, you're saying very casually there's a huge bug and security issue that no one else has detected but you personally have seem multiple times.
I've run into people on the internet misremembering things or not understanding how the browser works more times than I've run into browsers allowing access to system devices like the camera without a permission prompt.
I never said anything about granting permissions. I can respond to your other points, in turn, but first I would like you to confirm that I am who you think you are responding to :) I am not OP.
In case you don't think I'm OP, then, well I was being imprecise. Yes, it requires browser/app/manifest permissions. Your paranoid and aggressive tone implies you're not giving me any benefit of the doubt, as I speak informally in a casual web forum discussion about understanding what happened.