I don't think it's always part how GDPR is implemented in national laws. I believe it's admissable in court here in the UK, certainly my dashcam footage of a crash caused by a drink driver in 2019 was collected as evidence by police officers at the scene.
In Europe there are directives and regulations, and the former get transposed into local law, whereas regulations apply directly. The R in GDPR comes from regulation :)
