People might not be aware of what advice the police have given
Here it is from the Met Police statement:
Start
What to do if you have concerns an officer is threat to you / How do you prove an officer is genuine?
We completely hear the legitimate concerns being raised and we know women are worried. All our officers are concerned about the impact of these horrific crimes on trust in the police and we want to do all we can to rebuild that trust.
It is unusual for a single plain clothes police officer to engage with anyone in London. If that does happen, and it may do for various reasons, in instances where the officer is seeking to arrest you, you should then expect to see other officers arrive shortly afterwards.
However, if that doesn’t happen and you do find yourself in an interaction with a sole police officer and you are on your own, it is entirely reasonable for you to seek further reassurance of that officer’s identity and intentions.
Our advice is to ask some very searching questions of that officer:
Where are your colleagues?
Where have you come from?
Why are you here?
Exactly why are you stopping or talking to me?
Try to seek some independent verification of what they say, if they have a radio ask to hear the voice of the operator, even ask to speak through the radio to the operator to say who you are and for them to verify you are with a genuine officer, acting legitimately.
All officers will, of course, know about this case and will be expecting in an interaction like that - rare as it may be - that members of the public may be understandably concerned and more distrusting than they previously would have been, and should and will expect to be asked more questions.
If after all of that you feel in real and imminent danger and you do not believe the officer is who they say they are, for whatever reason, then I would say you must seek assistance - shouting out to a passer-by, running into a house, knocking on a door, waving a bus down or if you are in the position to do so calling 999.
End
news.met.police.uk/news/metropolitan-police-our-response-to-issues-raised-by-the-crimes-of-wayne-couzens-434739
I think it's laughable, completely unworkable and wouldn't have saved Sarah had she tried it...