Alistair .... any viewing of the recent unrest in the US lets us know that they travel with a posse of cell-phone toting 'Citizen Journalists' who can post selectively edited highlights on the web to 'prove' you were the fascist aggressor! .... 😁
Well tried propaganda training ...... the above, shouting "you're hurting/killing/suffocating me" loudly when restrained in any way for the benefit of the cameras, psychologically upsetting tactics (blowing horns in people's faces, constant shouting of hateful remarks close up etc etc ) to drive a response that can be framed as an 'attack on peaceful protesters' amongst others .... you can spot the script) ..... techniques to 'control the optic' shared internationally between groups.
You're right in one thing .... if they're not confronted/restrained in the act, then once they've walked away the possibility of redress is vanishingly small ... with all respect to the Police they'll almost certainly do nothing .... as the release and sympathy shown by the courts to XR protestors shows, why waste time on something with no realistic chance of conviction and very bad PR.
K