Apologies for putting this in here, but it is tangentially related, and I know there are lots of people who know things in here 
A hate crime (in Scotland, not checked rUK) is
Crime motivated by malice or ill will towards a social group by:
Race.
Sexual orientation.
Religion/faith.
Disability.
Transgender/gender identity
The protected characteristics are
age
disability
gender reassignment
marriage and civil partnership
pregnancy and maternity
race
religion or belief
sex
sexual orientation
Why are age / marital status / pregnancy / or sex not covered by hate crimes? Admittedly I don't think many people get abused for being married, but people definitely get abuse for being old, or a woman.