A bill to change the California Constitution to this effect, ACA-3, almost made it to the ballot. However, it didn't make it though the last minute rush at the end of the session, and is now "inactive." Hopefully, it will be revived in the next session. (See link below).

The California Labor Movement was actually succesful in putting a provision against prison labor in the 1879 Constitution. Just as with the original prohibition of slavery in the 1849 Constitution, the motivation was really to prevent slave (or prison) labor from competing with free labor.

But the prohibition of prison labor was flushed down the toilet by the voters in 1990., with Proposition 13.

The argument in favor of Prop. 139 was that prisoners should “pay part of their upkeep” and “pay restitution to their victims.” The opposite happened. Twenty years later, the costs of imprisonment skyrocketed, while the money from prison labor contributed only a third of one-percent (0.003) to that cost.

The text, history and analysis of ACA-3 can be found at:

https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=202120220ACA3

Especially interesting is the bill analysis, which goes into some of the same points you make here:

https://leginfo.legislature.ca.gov/faces/billAnalysisClient.xhtml?bill_id=202120220ACA3#