Broadly, in the space of anti-money-laundering legislation, it's recognized that politically exposed persons are in positions that are vulnerable to attempts to commit money laundering and related offences, including corruption and bribery. That's why Canada's legislation requires reporting entities to identify when their clients are politically exposed persons and to conduct enhanced due diligence on high-risk politically exposed persons.
In this case, the proposed amendments to the definition of politically exposed persons are to specifically include positions equivalent to a mayor. These would help clarify the definition and achieve the overall public policy objective of including public officials of leading organizations with control or influence over large amounts of public funds due to the nature of their position.