Locker searches are legislated by state and by school. The ACLU has a page regarding student privacy: https://www.aclu.org/other/students-your-right-privacy and various state chapters have additional information, e.g., https://www.aclunc.org/our-work/know-your-rights/searches-of-students. That’s what the ACLU says about lockers and privacy.
Regarding separation of families; there was never a law mandating separation. Even if there was a stated non-legal policy, it was rarely or ever done. The stated policy of separation is supposed to be a deterrent as stated by Kelly a few months after Trump took office. A modicum of research and archival searches explains this pretty easily.
Seems like the “snowflake” label works both ways sometimes.