A San Francisco second-grade teacher who, due to state law, must pay the cost of a substitute educator while she seeks treatment for breast cancer has made national headlines after parents at her school started an online GoFundMe campaign to cover her costs. “Parents were outraged and incredulous—like, this can’t be. There must be some kind of mistake!” one parent told the San Francisco Chronicle. But the situation, which has outraged parents and captured the attention of state lawmakers, isn’t…