I can speak from experience and the experiences of many defense attorneys. Many of my clients spent time in jail and then the government decided not to file charges, or the charges were later dismissed, or they were acquitted of the charges at trial. This is is a good resource for additional information on the number of people impacted by the criminal justice system: https://www.prisonpolicy.org/reports/pie2018.html and this is a series on netflix that highlights some of these issues: https://www.netflix.com/title/80187052