That section is generally intended for Diplomats or officials applying through embassies or international organizations or Applicants involved with official government missions or People sponsored by Thai government agencies or international organizations.
What they could be looking for is a letter from your Thai family member, their ID cards and proof of relationship.
national origin hasn’t nothing to do and not being able to open a bank account in Thailand on a tourist visa. No European country would allow a tourist to open a bank account so why are you expecting Thailand to do it?
Discrimination is the unfair or unequal treatment of individuals or groups based on characteristics such as:
• Race or ethnicity
• Gender or sex
• Age
• Religion
• Disability
• Sexual orientation
• National origin
• Social class
It occurs when people are denied opportunities, rights, or fair treatment because of these traits rather than their abilities, behavior, or qualifications.