Joke Collection Website - Public benefit messages - Why do yellow messages have their own names?

Why do yellow messages have their own names?

This is a scam message.

Criminals send fraudulent short messages through overseas mobile phone numbers (+0082 is the overseas number), claiming to be the staff of the service hotline of the Social Security Bureau, and the contents are "Abnormal social security cards will be forcibly terminated" and "Social security cards will be upgraded". This is a scam message, please don't believe it.