It won't be about results at this stage
Dick said earlier this year that she didn't think it would result in lots of arrests
No, but it'll collect a helluva lot of useful facial data for various state-sponsored AI systems to practice on, so imagine if they compared the images with say the Passport Office database, or maybe TFL cameras? If Joe Bloggs was a regular tube user and they captured his image via one of these vans they could easily judge the accuracy.