When attacks are by Islamist extremists, they are labelled as such. e.g. the Manchester Stadium bombing, the Manchester synagogue attacks.
When they are attacks by disturbed, but not radicalised individuals, they are not labelled 'terrorist' attacks, e.g. the tragic Southport attack by Axel Rudakubana.
Do you see the difference?
Violent crime is analysed for its motivation, which is why when the father of this girl noted she was coming out with violent Reform ideology we now know that she was being radicalised into committing a hate crime.