Data isn't free and processing big data isn't cheap. As much as Google has the data, that means they need to store that data.
You know what used to happen before and still happens now, an example. I live in a restricted access area. Restricted in the sense rhat to get in some guy needs to take your name and license plate.
For many many businesses parks in my country that is still the defacto. There isn't really a camera watching that other than general CCTV that probably doesn't have the resolution to pick up text on our license plates. It's cheaper for them to literally pay a guy to stand at a boom and get that information than to install the technology required to track that automatically.
The adtech industry made data and its processing not just free (as in more than covered by the ad revenue) but outright profitable.
This is frankly a one-in-a-lifetime gift to the government because we've not only built an unaccountable industrial-grade spying machine but the government doesn't even have to pay for it as it pays for itself and incentivizes its own expansion.
It depends of the local cost of labor, also the technology is easier to scale, imagine New York City having employees at the bridges writing all the entering license plates! And searching through those records how many times a certain plate entered the city on a given time frame. To me the problem with technology is that they’re used for lazy policing to just inflate the numbers of solved cases. There were cases of cops feeding hand-drawn suspects to face recognition software. Every case becomes a “throw something to the wall and see what sticks”.
Legitimately if an investigator put a hard drawn sketch through facial recognition and that was even remotely allowed into evidence by the court then the suspect evidence wasn't the issue