Earlier quoted context omitted.
Penalty length has very little effect on crime motivation. The most important factor is the likelihood of getting caught. You want to see crime rates drop? Shift a large percentage of the prison budget to the police.
It's not "likelihood of getting caught" because even if you have a 1 in 5 shot at getting away with a crime, desperate folks (or folks with a shaky understanding of probability) will still take the risk. It has to be "certainty of getting caught" which requires more than just more police, but also public messaging, education, etc. See: https://www.ojp.gov/pdffiles1/nij/247350.pdf
1. The certainty of being caught is a vastly more powerful deterrent than the punishment.
2. Sending an individual convicted of a crime to prison isn’t a very effective way to deter crime.
3. Police deter crime by increasing the perception that criminals will be caught and punished.
4. Increasing the severity of punishment does little to deter crime.