Can you explain why sex isn't included?
No. I'm not a criminal lawyer. The distinctions throw up various anomalies. This has been discussed at length before on here. Belgium has the widest category and under Belgium law pickling on some one simply because they are old or ugly or stupid or poor or posh or a bit weird is covered along with the other categories.
Sex is a protected characteristic so far as discrimination for employment, provision of goods and services.