It costs a lot of money to conduct an investigation. There's no guarantee of success at that stage and that's well before mediation, or case management.
Even if one proves wrongdoing, they'd need to spend a lot of money to sit at the legal table. The question is how much is one prepared to spend to try to prove fraud / conspiracy / whatever...
Bear in mind the out-of-court settlements insurers often go for. Not because they're necessarily wrong, but because its commercially practical to settle without going to trial.
The paradox of iHub: buy high, sell low