That’d rely on tenants reporting their evictions to the tentants’ union, and most people aren’t engaged with the tenants union, and even among those who are, relying on tenants reporting would probably be a bit spotty.

If the government is serious about enforcement, I think the logical thing would be for the bond authority to track it. They could be required to log the reason when the bond is claimed, and then their system would flag it if another bond was lodged for the address within the specified period.