The burden of proof has nothing to do with the admission (or not admission) of wrongdoing.

A settlement is a way to end a dispute by agreeing to a solution, in other countries it is "normal" that a party admits (partial) responsibility and pays to the other party a (monetary) compensation and the other party accepts the compensation and promises to refrain from further actions in court.

In such cases the admission is the actual reason why the compensation can be given to the other party.

The way these class action settlements are closed seems like one party did nothing wrong still it gives money to the other party (why? because they are generous?).