I'm not Belgian, I just had to deal with them extensively, so I can't reply. But the credit score is not related to the existence of the national ID.
I know that the monstrous institutions thriving on the FICO score are an exception. In most countries, it's the usual payslips, bank statements, stuff like that. No one needs weird stuff like secured credit cards or asking their relative to "piggyback" on their credit score.
I know that the US credit agencies tried to "educate" the local business communities in some countries on the importance of the credit score and are currently occupying a small obscure niche.
I know that the monstrous institutions thriving on the FICO score are an exception. In most countries, it's the usual payslips, bank statements, stuff like that. No one needs weird stuff like secured credit cards or asking their relative to "piggyback" on their credit score.
I know that the US credit agencies tried to "educate" the local business communities in some countries on the importance of the credit score and are currently occupying a small obscure niche.