G4S, being a private company, only have incentive to increase profits, not do what would be the right thing. I would expect these things to be handled directly by an accountable person. Otherwise, before we know it, everyone is wheeled into court "Hannibal Lector"-like.
G4S being a private company working for government increase their profits by providing the services that the government are willing to pay them for. If they're not incentivized to do the right thing then that's down to the government asking for the wrong thing. In this case, they're incentivized to keep the public safe - which is what they are doing.
