Is it spying when you're just not turning off automated systems that nobody looks at the data for? It's literally no different than what Google does for anyone

Is it spying when you're just not turning off automated systems that nobody looks at the data for? It's literally no different than what Google does for anyone else, yet it's spying for schools because... why? Were the children using the services under 13? I've never understood why this was potentially illegal, and never seen anything address that.