In CA, it’s because Newsom doesn’t want that. What parents in my district are doing is working on recalling the school board, which is in the pocket of the unions. School boards at times go even further than the state in keeping schools shut. And SF and LA are now suing their respective school districts. The districts can blame the unions but they and the governors are allowing this.
Actually, the districts can blame the unions. The collective bargaining agreements have stipulations about healthy work environments, and the exaggeration of the dangers of COVID have given them an excuse to claim danger.