In a weather-proof, UV-resistant housing, with battery and solar panel for charging, designed to meet municipal and traffic safety specs, and with turn-key service, all at the usual markup for dealing with all that and because there are almost no competitive alternatives, it sounds pretty typical.
Even a simple stop sign is hundreds of dollars when you consider all the costs associated with its installation.
And the cameras Flock are using are no where near that good of quality. The claim was high quality cameras are expensive. Flock is using pretty cheap components. There's been multiple tear-downs showing just how budget built they are.
Yes, stop calling them "ALPRs" because they're not. It's the surveillance industry's marketing wank to make them seem benign, limited, and a police tool when it's (and similar products) really a video/audio?/wifi?/bt?/sdr?* panopticon that generates fallible metadata about maybe you, maybe your car, and maybe your stuff that will be saved forever, to be offered for sale forever to almost any company, government, or individual in the world with money for any purpose.
They say they'll delete "data" in X days, but what they really mean is original source video only. There's no guarantee they'll delete anything else because their moneymaker is compiling sellable "histories" of and AI training data about people, vehicles, and other objects.
Streetlight light sensor ports are being used to retrofit lights with smart lights containing advanced neighborhood spy "cameras" with additional features. So there's more than just standalone or telephone pole-mounted "ALPRs".
* It's not a huge cost and there's obvious motivations to iterate to include additional sensors &| radios to gather additional raw data by using the fleet of "ALPRs" as a platform. Many "ALPRs" have microphones. Some smart streetlight ones do wifi/bt fingerprinting.