I read a half of the article and it doesn't seem to mention where from, but all you need is a camera with image recognition. Number plates are much easier to spot than faces since they are very uniform and flat and would only be translated in an image.
I've seen these cars in the Cincinnati area. They're using the same technology (Cameras, at least) that the Law Enforcement folks (Ohio State Highway Patrol) are using, but on a 4 year old Honda Civic versus a Crown Vic/Dodge Charger/Chevy Impala.
An iPhone camera isn't really good enough to OCR vehicles as you move past them in a parking lot. You get skew from rolling shutter effects, plus it's going to be shaking violently when attached to an automobile without proper dampening.
The cameras used for OCR on license plates need to have a fairly high resolution, fast shutter speed, and a number of other little additions which make it more expensive than an iPhone camera. Granted, $10,000 is really expensive for such a device, and the real cost for something like that is probably a few hundred dollars, but after you add in software and radio communication (probably a cell plan if I had to guess), you're looking at an expensive device.
Of course, we could build one ourselves for a fraction of that, but that's why we don't drive tow-trucks or license plate scanner cars for a living.
In the same way an iphone can be good enough for your wedding photos?
These are high quality cameras, that have to work in large range of weather and lighting conditions. This cost might also include the software to OCR and store the details.
Correct, these work in inclement weather, in various lighting conditions, at high speeds (60 mph down the highway), and include computers that OCR, extract the plate number, match against a large database, and notify on a dashboard laptop if a hit occurs. They also often include multiple cameras (e.g. to capture cars parked on the left and the right of a street.)
One of these companies does in fact have an iPhone app that police officers can use to query a national database, but it can't scan 1800 plates per minute as you cruise down a highway.
Also note that they help local and state agencies obtain grant funding from federal sources, so I'm sure there's a bit of cost-cutting that could occur in a less bureaucratic and funded market. Also, these were like $30k 10 years ago, so prices are falling.