>Wouldn't the affected individual be able to sue the provider at least in some cases?

And lose time and money, which they also likely don't have?

Both SCA and 18 U.S.C. §2712 can grant punitive damages and attorney fees. So there might be lawyers who would take it on contingency, and in this kind of case some non-profit could also have interest in litigating the issue.

And as this is something that has already happened there isn't much else the person in question can do. Third parties always have option to just disclose information to whoever asks it, at most you can hold them accountable for it later if it was unlawful. And what accountability exactly means depends on what laws exists. If you want some real accountability for the people/companies involved in these kinds of decisions then get Congress to pass such laws (however impossible it might be).

If you go by this logic, you can forget the entire legal system. You might as well immediately close all lawsuits and declare the party the winner that has more capital.

It doesn't (yet) work that way.