I tried to come up with a reason to justify a door camera. I couldn't.
If the doorbell rings, and I'm not expecting anyone, then I don't answer it. It doesn't matter to me who it is. I don't need to know.
Also, if I don't answer and it is someone I know, they can call me from my doorstep and let me know it's them.
If a package gets stolen off my doorstep, which has never happened, and doesn't happen much here at all as far as I know, the video is of zero use, unless I know who it is. Because, the cops sure don't know who it is, or even care to find out. You might think that's their job, but you'd be wrong. Their job is to take the report and file it. That's it.