How screening evidence weakens down a chain
A venue contracts a cleaning company, which engages a labour hire firm, which may itself draw from another pool. At each step the assurance becomes more general: the venue is told the workers are screened, the cleaning company relies on the labour hire firm's statement, and the labour hire firm relies on whatever its own supplier said. Nobody in the chain has verified an individual, and everybody has honestly reported what they were told.
The result is a venue holding evidence that describes a process rather than a set of people. That distinction only matters when something happens, at which point the question is not whether screening was required but whether this particular person was screened. Chains that cannot answer that question have provided compliance in appearance rather than in substance. It also means a venue asking for improvement after an event has nobody specific to raise it with, since the individuals involved may never return.
