Some good points here.

I think Sasaki was trying to assert (and I agree) that the higher per capita rate of imprisoned persons does not, of itself, mean that the justice system is flawed. If more persons commit crimes, more are likely to be caught, convicted and imprisoned for crimes committed.

Now, there are EXCELLENT arguments to be made (some have been already above) as to whether harsher sentencing is achieving the objective of minimizing crime and recidivism or not, as well as questions regarding race and prison sentences imposed. There are, also, potentially huge issues regarding cultural attitudes and norms vis-a-vis incarceration.

I'd suggest that a higher overall rate of incarceration when compared to Europe may be more symptomatic of cultural difference than qualitative difference in the system of justice.