You realize you don't even need a flight plan to operate manned aircraft, right?

No, I didn't. Perhaps that should be changed.

In any case, if there's a drone flying over my house or a public space doing something unsafe or legally questionable, it ought to be possible for me to make a call and have it investigated, knowing that there's a licensing trail to follow. Likewise for operator training.

If drones operate with impunity, we can expect more people to take things into their own hands.

Yes, But a manned aircraft can not hover outside my bedroom window in my backyard

As someone who used to live in a neighborhood that was frequented by "ghetto birds"[1], I have anecdotal evidence to the contrary. I think the main difference between a consumer multicoper and a helicopter is the barrier of entry to purchase one (and become qualified to fly it) and the operating costs

[1]: Ice Cube once wrote a song to express his frustration w.r.t. how police helicopters outside his bedroom interfered with his sleep schedule: https://genius.com/Ice-cube-ghetto-bird-lyrics

Neither can a drone. That's already illegal. Filming into someone's bedroom is usually a felony.