The article does not claim this:
"The Metropolitan Police say that around one in every 33,000 people who walk by its cameras is misidentified.
But the error count is much higher once someone is actually flagged. One in 40 alerts so far this year has been a false positive"
These are 2 different metrics that measure 2 different things and so they are both correct at the same time. But I must say I am not clear what each exactly means.