The important question, only important question IMHO, is how they handle positives. Do they go all guns blazing and arrest the person on the spot? Or do they use a restrained approach and first nicely ask the person if they have any ID, etc? That's the important bit.
What if your child falls victim to a false identification, and then given that children are far less likely to have some form of ID on them than adults, they're stuck for much longer?
Do you trust the British police to take good care of your child? Or will they strip-search her and threaten her with arrest like they did with the then-15-year-old Child Q because they decided that she "smelled of weed"?
Do you really want more unnecessary interactions with the police for yourself or those you care about when your "suspicious behaviour" was having an algorithm judge that your face looked like someone else's?
This is nothing new. It is all about what is reasonable in the circumstances.