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.

Here's an example large manufacturer of these: http://elsag.com/mobile.htm

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.

Parent's point was valid though, I can't imagine these devices to cost more than $170 in a couple of years, making this discussion quite relevant.

Until the cost of grinding glass comes way down, this won't be true.

They don't need pictures that look nice. They just need to extract information from them. Better image processing will facilitate this.