Custody credits. For crimes committed after October 2011, defendants who do not misbehave while in jail will receive 1 day of "conduct credits" for every 1 days of actual jail time served. Felons will similarly receive 1 day of conduct credit for every day of actual time served in prison while on good behavior. However, felons convicted of a violent crime only receive 15% conduct credit for time served (so 1 day of "conduct credit" for every 15 days of jail time served) and 0% credit if convicted of murder.
The only crimes you can (or could) receive 30+ year sentences for in CA are violent crimes (like rape, armed robbery, or murder) or 3-strikes sentences, and such sentencing is no longer possible for a 3rd strike unless the 3rd strike is a violent crime.
So lawyers game this so that the felons stay in these prisons/jails longer than other prisons and come out faster.
The police officer is lying. Credits are based on statutory formulas and no facility provides any more custody credits than any other, because the facility doesn't determine how many credits you get.