I'm not quite understanding this. What is there to be gained by raising the stakes? Doesn't it make defendants even more determined to seek justice?
Suppose the threat is 10 years in Jail. You reckon there's a 1-in-a-million chance they can convict you since you're innocent and they have no evidence. The plea offer is $100 fine. That's a good deal, not taking it on principle is a stance I admire but it does not make good logical sense.
What the US needs is a strong incentive for prosecutors not to take cases they expect to lose. That wouldn't really fit with the rest of the US "justice" system though.
At least until the recent tough-on-crime regression almost everybody agreed the system is too harsh. Even conservatives were on board with lighter sentencing. But unsurprisingly that broad public support didn't persist for long because the structural incentives of the system push it toward greater dysfunction. Without structural changes lighter sentencing alone just makes it more profitable for criminals to roll the dice. The complexity of the system evolved with the harsher sentencing, but can't change back as easily as sentencing policies, so we fall back to the old equilibrium that slowly gets worse along every dimension--fairness, cost, deterrence, etc.