Digital ID is optional by default. Service providers that integrate with the Digital ID can apply for an exemption to make it mandatory. Given the mandatory nature of age verification checks for social media, the fact that social media is typically free to use and ad-supported and the cost of age verification would be prohibitive for smaller apps without significant VC backing, an argument for exemption could be made on the basis that their legal obligation can't otherwise be fulfilled without a prohibitive upfront cost.