Some of its standards supersede national law (I think it was the regulations that did so, amd standards needed to be built into national law, could be the other way around).

And this makes a lot of sense with rules about food safety, product standards etc. It almost makes sense for privacy protections. It makes very little sense for surveillance laws.

Governments also codify into law that everything X standardizes is automatically a regulation for other standard bodies. Road and building standards work that way: they are just standards issued by a random association and the government has stated, that all developments in their jurisdiction need to follow this associations standards.

The government could also do this for the EU, it's called leaving the EU.