This is warehouses and maybe customer service hotlines we're talking about. The work is fungible and the teams are large enough for it to average out. I'd also

This is warehouses and maybe customer service hotlines we're talking about. The work is fungible and the teams are large enough for it to average out. I'd also argue that because of them being a drag in other work environments, there already is enough social pressure to keep "fake" illnesses low. Humans are surprisingly sensitive to the disapproval of their team/tribe.