Have these actually been tested in court? I believe if someone actually decided to sue it would go about as poorly as non-compete clauses in employment contracts.
Yes, SCOTUS has repeatedly upheld binding arbitration clauses as valid, and that they even override state law and apply in cases of naked fraud by the company:
In a sense this is just codifying what has always been tacitly true - the court system isn't really intended to protect the common man against the economic, political and social elites, it's primary purpose is as a dispute resolution mechanism among those elites.