SPAR loyalty programme - ID NO required

Spar Rewards, forces you to insert your ID number to get the updated rewards card. I do not want to share my ID number for a loyalty card and my question is , what does SPAR benefit from collecting this personal information. In terms of the new information age surely I should have the option to not submit my ID as no one will ask for identification when I swipe at the shop. They then had an email address "***" where you could log complaints but this email did not work . Spar in future Id rather shop with a loyalty programme that does not require my ID