This. It's all within a democratic and legal framework, from GDPR to organisational policies. The source is the police themselves informing the public of the trial. The actual camera setup is bright yellow in the middle of the concourse, it's not hidden. They haven't hidden this technology, a private company hasn't deployed this technology. As citizens you have some control. It's probably not perfect, but there's humans in the loop. You have recourse to complain, to write to your PM, to take a different route (because they are pre-warning you). This IS democracy.