Since nutrition standards were strengthened in 2010, eating at school provides many students with healthier food than is available cheaply elsewhere. Plus, reducing stigma increases the number of kids getting fed.
Because once we start doing socialism for kids, people will start asking for socialism for everyone, and the ultra rich wants to keep that under control.
You're right. It's better than free. It sets those kids up for a healthier life, making them more well rounded into adulthood. It's a highly returning investment in our future.