"Enforce a lower rate of interest I presume."
The presumption is incorrect. High risk cases are unable to borrow from regulated institutions.
Rate-capping in France and Germany has resulted in legitimate lenders not catering for the large section of potential borrowers who need to borrow less than the minimum loan amount that the capped rate makes financially viable for the lender to offer (often around €1500) and who do not qualify for this higher loan amount because of their risk status. This is why the incidence of illegal lending in Germany is 2.5 times higher, and that in France is 3 times higher, than in the UK. Enforcement by illegal lenders may involve the use of a baseball bat.