Because you can't boil a frog by starting at 100°C.

You introduce the surveillance as a way of mitigating extreme, rare occurrences, like terrorism.

You gradually make it common to use when solving major crimes, like murders.

Only then do you start tracking down traffic infractions.

Doctorow calls this the 'Shitty Technology Adoption Curve' https://pluralistic.net/2022/08/21/great-taylors-ghost/