I think my point may have not been clear. I was responding to someone who offered a theory that it is legal because it reduces the cost of having trials. The implication is that it was decided at some point that we should allow it.
My point is that because it is implied by freedom of contract, it is by default legal until we decide to make it illegal.
> it is by default legal until we decide to make it illegal.
No, it's legal because of the Federal Arbitration Act passing in 1925. Prior to that, waiving of such rights "in advance by agreement" was explicitly disallowed, as SCOTUS determined in Insurance Company v. Morse (1874).
My point is that because it is implied by freedom of contract, it is by default legal until we decide to make it illegal.