There are reasons that "1984"(sic) and "V for Vigilante"(sic) were set there
Yes. Because the UK has a disproportionately high number of a good writers, and both Eric Blair and Alan Moore live(d) there.
Note also that they don't actually *use* the CCTV's to fight crime. They use them for bureaucratic monitoring, such as insisting that people pay the tax for cars in London, or that they park correctly. They're not used for pickpocketing, luggage theft, or even prosecuting vandals.
They use the CCTV for all of those things. I think you've been reading too much Daily Mail.
(Those personal crimes are not considered "important enough" to justify checking the video records. Been there, done that.)
They tend to use the CCTV live. To guide cops to the places where these things are happening. Combing back through recordings is a different matter, with a different balance. It's a significant use of resources to comb through the video, and then the individuals are long gone from the scene of the crime, and are unlikely to be easily identified. It obviously won't be worth it for for petty crimes. But it is done for more serious crimes.
Not that I'm in favour of all the CCTV. But lying about the uses it's put to isn't helpful.