Ofcom is the designated regulator and has the power of enforcement. The law doesn’t define what it set out what age verification means, only that they much be ‘highly effective’ (Section 12 (6)). It is therefore left to Ofcom to set out in its Code of Practices (Section 41 (3)) what ‘highly effective age verification’ means, which is what this guidance is. This isn’t Ofcom being nice, this is them telling you how they’re going to enforce the law.