A close friend has been a public defender (criminal defense attorney) for 20 years. In her experience observing 20 years of cases, there's a direct correlation between wealth of the defendant and likelihood of getting off.
"The unspoken reality is that in America today there exists two systems of criminal justice. One for the wealthy, which includes kid-glove investigations, lackluster prosecutions, drug treatment, light sentences and easy, if any, prison time. The other, for the poor, is one of paramilitary policing, aggressive prosecution, harsh mandatory sentences and hard time. Wealth, and the political connec tions inherent to wealth, not race, is the determining factor in deciding which system one gets. This is most obvious when wealthy hip-hop artists and athletes, many of them black, are charged with serious crimes. Class trumps race every time, even if the wealth is new found..."
"... corporations can and do commit high crimes and misdemeanors with impunity. Likewise for governments and their agents, such as the police or military." — https://www.prisonlegalnews.org/(X(1)S(z3ez5uic5qiulf453pf34...
If this holds true for a black guy caught with a gun in NYC, why think it doesn't hold true for a finance guy conspiring against his clients?
Cheat your bookkeeping clients out of 10 grand and you're in the slammer, cheat cities or nations out of 10 billion and you might lose a couple tee times at the country club for depositions.
But your point is well taken.
> lawsuits must be lawful
It's not the "rule of law" part that's naive, it's the "democratic" part. We still have some semblance of the rule of law (although even that is starting to fray) but there is no more democracy in the U.S. We are a plutocracy, a government of the wealthy, by the wealthy, and for the wealthy. So it is unsurprising that what the banks are doing to rip people off is legal: the banks (and other big businesses) write the laws.