This is incorrect. Prop 47 didn't decriminalize shoplifting. It actually criminalized shoplifting.
Prop 47 created California Penal Code 459.5, which created a criminal offense for shoplifting. Prior to the passage of Prop 47, shoplifting was charged as Petty Theft; there was no shoplifting criminal offense on the books. Every other state has a particularized shoplifting offense. In
Massachusetts, where I am a prosecutor, we have had a shoplifting statute on the books since 1981.
Petty theft is a misdemeanor,
punishable by 6 months in county jail. After passage of 459.5, the punishment for shoplifting is the exact same, 6 months in jail. Also that $950 threshold is no especially high bar and was in keeping with the prior theft criminal code. The threshold for Petty/Grand Theft is $950. This threshold was last increased in 2010 so its not a recent increase. Reviewing the statute and the language of Prop 47, that $950 shoplifting threshold was picked to keep it in line with the already established petty/grand theft threshold. Other states actually have higher thresholds. For instance, in
Arizona, the threshold between a felony and misdemeanor shoplifting is $1,000.
In fact, 459.5 might have allowed for more (or at least earlier) law enforcement intervention. Comparing the definitions of theft from the California Penal Code versus shoplifting, the difference is asportation. Here is the definition of
theft (regardless of petty/grand): " Every person who shall feloniously steal, take, carry, lead, or drive away the personal property of another...is guilty of theft." Here is the definition of
shoplifting: "shoplifting is defined as entering a commercial establishment with intent to commit larceny while that establishment is open during regular business hours, where the value of the property that is taken or intended to be taken does not exceed nine hundred fifty dollars ($950)." Prior to the passage of Prop 47, the crime of petty theft was not completed until the person carried away the property. California Penal Code 459.5 states that an individual has committed the crime of shoplifting once they enter into a commercial establishment with the intent to commit larceny. It doesn't matter if they actually steal it or not.
These sort of distinctions matter in granting a shop owner or employee the right to detain a shoplifter. If the crime isn't completed until after they have left the store, the employee has to detain them on the street or the at the very least toward the front, past the registers. This may create an incentive to bolt since the exit is close. If the crime is completed before (like in 459.5), they can can detain them well in the store. The last important note is that while shoplifting is a misdemeanor, it can be elevated to a felony based on the offender's criminal history. However, law enforcement/prosecution isn't going to know that until they make the initial arrest and can run the offender's criminal history. So the argument that "police won't respond/DA won't prosecute because its a misdemeanor" is untrue.
So TL/DR, Prop 47 criminalized rather than de-criminalized shoplifting. The threshold is in line with the prior theft statute on the books.