Financial services regulation is predominantly organised nationally or regionally, with distinct legal systems, supervisory powers, and sector structures; consequently, authorities have each developed schemes that fit their own regulatory context, even while drawing on shared underlying methodology and, in some cases, direct collaboration and cross-pollination of ideas between schemes. This reflects genuine differences in regulatory architecture, not a legal prohibition on harmonisation (B), it is not accidental (D), and it does not stem from rivalry between CREST and the ECB (C) - these organisations play complementary, cooperative roles across several of these frameworks.