Ah, I see. Then I'd argue that which applies to masking, similarly applies to tag obfuscation. And ideally the plate would remain readable in case of disputes (as would recognition of a face), but mass-surveillance systems have taken that nuance from the equation.
If overall collection of personal data isn't a concern (which it is for me), and the focus is solely on sabotaging automated systems: clothing with confusing patterns may throw off classifications, IR glasses might impair facial recognition, and dirt-like noise atop license plates might hinder character recognition; but the irony is, that one likely draws more attention to themselves in doing so (an officer being alerted upon failure, and likely required to manually review: potentially leading to an actual investigation).
I don't mind what most ordinary people know about me, unless they'd systematically collate those activities: especially for the purposes of exposing underlying patterns. If the persons involved or activities carried out weren't memorable, they are likely to be forgotten. And generally speaking: observations by an untrained person are hardly reliable, and they certainly lack the resolution of digital counterparts.
But that lack of anonymity directly translates to a potential privacy-implication. You may also argue that nothing is private, because you could put a gun on a person's head, and force them to give up any secret they have. Surveillance is equally involuntary, and similarly exposes details about one's private life, which where traditionally very unlikely to be extracted.