I don't really care too much one way or the other about these cameras, and generally think it's probably bad to have more surveillance but could you help me understand what exactly is "unconstitutional" or even nefarious with these cameras provided they are bought and installed on property that is owned by the installer or an entity such as the government which presumably has legal justification for installing them?

I'm genuinely asking since I'm a bit out of touch with this latest controversy, but how are they any different than a dash cam, doorbell camera, or my alley camera, for example such that they deserve special consideration?

It's the database query, not the physical cameras. In the pre-digital age where privacy was considered in constitutional law, tracking people's and vehicle's movements was horrendously expensive - you'd need multiple detectives doing things by hand per person of interest. This meant that it was reserved for when the government already had pretty strong reason to believe in some sort of wrongdoing. Even with a personal, non-internet-connected doorbell camera, the police would need to identify what cameras exist for a location and contact the owners in order for the footage to do anything.

With automated license plate readers, they can simply collect everything with a reasonably affordable network of cameras, then query the database when they want to find a particular pattern of activity. The police have already detained people for frequent border-crossing between marijuana-legal and illegal states. This gets exacerbated by granularity and extensiveness - imagine an anti-choice state pointing cameras at every maternity care parking lot in the state and tracking who visits them for cross-referencing with visits to pro-choice states.

And with the existence of parallel construction, there's no reasonable way short of dismantling the ALPR system to avoid abuse against the citizenry.

It’s an interpretation of the Fourth Amendment, which is loosely supported by Supreme Court precent in Carpenter and Jones. See my previous comment: https://news.ycombinator.com/item?id=46359826

Edit: To be more clear, the issue courts have considered is warrantless searches of ALPR databases (and whether that evidence should be excluded), not whether it’s constitutional to put up cameras.

The constitution forbids unreasonable search and seizure. Tracking people's movements without specific reason the believe that they are a criminal has generally been regarded, at least by the public, as a classic example of government overreach.

They are not unconstitutional. There is no right to privacy in public. There's endless confusion online, but legally, public means "not private."

SovCit/Libertarian types love treating "Constitutional" as a kind of magic spell. I wouldn't worry about it too much. They're more beard than people.

I can only assume this question is disingenuous.

"What is so wrong with having your house burn down? It's just a chemical process that happens all the time."