The procedural protections of the criminal justice system are weaker in many developed countries outside the US. E.g. Italy where you can keep trying someone for murder until you get the result you want. What makes the overall system worse in the US is how militarized the police are, how over the top aggressive prosecutors are, and how long sentences are.
Italy is bananas. A few years ago I accidentally drove a rental car through a ZTL in Rome. Some months later I received a letter in the mail at my home in the U.S. asking me to pay the fine (even though I had already paid it to Avis). What was astonishing was that the ticket said you were allowed to contest it, but if you contested it and the authorities decided against you, the fine would significantly increase.
According to Pfaff, It's mostly the middle (how aggressive --- and also how poorly allocated --- prosecutors are), and very little the latter (although sentences are clearly too long).
If we're comparing the US criminal justice system to other countries, another more fundamental problem we have is that we simply have more crime. Not "people are getting busted for weed" crime, but property crimes and violent crimes. That fact implicates a much broader spectrum of public policy critiques about the US than how we manage the criminal justice system.