How familiar are you with Content Security Policy in browsers? It is designed precisely to protect user privacy. I don't know what you mean by 2. Do you mean

How familiar are you with Content Security Policy in browsers? It is designed precisely to protect user privacy. I don't know what you mean by 2. Do you mean that sandboxes can break? If so that seems like a very weak point. The browser sandbox is very secure. Furthermore, similar critiques can be made of free software. Someone could sneak in malicious code into free software.