They do not base changes to the curriculum or teaching methods on evidence. They could roll stuff out at a few schools, measure impact, and only expand the best programs, but instead they make changes based on what is fashionable that year, with predictably bad results.
School funding (at least in California) has been diverted somewhere else. I’m not sure where it goes exactly (education income taxes are supposedly earmarked at the state level, and the education fraction of our local property taxes must be spent outside our district — I’ve seen the district budget, and know how many houses it serves). Anyway, K-12 is embarrassingly underfunded, especially given how rich this state is. As a side effect, there isn’t funding for enrichment programs, and the school mostly just focuses on behavior problems instead of academics. Some of the kids that act out the most are clearly smart and bored.