One thing I noticed is that lax laws create more criminals. For instance, on the D.C. metro they used to take fare evasion very seriously, and you almost never would see people jumping the fare gate for the metro. Then a few years ago, the Council decided to decriminalize fare evasion. No you see tons of people just openly stepping over the gate every day. If they ever want to tackle the problem, they're going to have to have _much_ more enforcement, because now there's probably 100x or 1000x the fare jumpers than there used to be.
Many places in the U.S. allow a certain level of criminality, which not only encourages criminal behavior, but means the people involved only face consequences when they do something truly horrendous that brings a long sentence. Let a teenager walk free when they steal cars, and they end up killing the next person they steal a car from (happened here recently). Never charge a stalker when he assaults his stalking victim multiple times while on probation, and he eventually kills her (also happened here recently). Let someone simply walk away from the court after being convicted of an armed robbery, and they'll eventually murder an innocent (again - happened here recently).
It can take years to undo this. We started moving in the right direction - cracked down on crime, brought the crime rates down, which started bringing down the incarceration rate. But then people got impatient and wanted undo everything, with many big promises that never materialized. Now crime rates are up, and we're probably going to end up with more incarceration.
Many other countries have lower incarceration stats. But in my experience, the people in those countries are often shocked when they learn that in nice neighborhoods of the U.S., large groups of men can walk into a store in the middle of the day, openly fill up bags of stolen merchandise in front of everyone, and simply walk out with no consequences. The base level of crime that's accepted in many places in the U.S. is simply much higher than in many other countries.