> Federal prosecutors won't even pursue cases unless they think there's a high chance of success.

The problem with this theory is that it ignores the incentives on the other side in a criminal case. When you get charged with something, the prosecutor offers you a deal and that deal is almost invariably a significantly lower penalty than what happens if you go to court and get convicted. The plea deal is a lesser charge, if you demand a trial then they throw the book at you, stack charges and ask for more severe penalties for each one.

With the result that if someone actually did it, demanding a trial instead of pleading guilty for a lesser sentence has a large negative expected value. Which in turn implies that it doesn't make sense to do unless you think there is a high probability you can win, for example because you know you didn't do it. The coercive force is so large that it can cause innocent people to plead guilty, since even a 10% chance of losing can screw up your whole life when it means a 10x higher penalty.

And yet > 90% of the people who thought their chances of being acquitted were high enough to be worth taking a much large sentence on conviction, still get convicted. Which seems suspicious.

What youre saying is true, but the reality is that the number of people actually affected by it is vanishingly small. Of course its not vanishing if youre that person affected, but as far as the system goes, its negligible.

The reality is that most people who become subject to criminal prosecution are guilty. The reason can often be attributed to overbroad laws, but that still means you are guilty and will likely lose your criminal case. The prevalence of plea deals is just a performance optimization on top of that fact - most people are guilty at that stage and we'll let you off a little easier if you avoid the time and cost of a trial.

Innocent people are coerced to plead guilty, but you also have to realize the number of "innocent people pleading guilty" also contains guilty people who convinced lay people, who never saw or reviewed the evidence, they were innocent. As a prosecutor during a plea negotiation I once almost dismissed a charge against a girl who convinced me that she was innocent until I actually looked a security tape before signing the dismissal. She was 100% guilty. This is another interesting point about how busy prosecutors are - i didnt even bother to review the evidence against her before offering her a plea deal.

All this to say, if you end up coerced into accepting a plea deal despite your innocence, you are not a normal person. Yes, there's at least one normal person out there who was coerced, but they're the exception that proves the rule.

Courts need more funding, laws need to be relaxed and fine tuned, we need to stop the school to prison pipeline, but even with all those problems the system works pretty damn well.