Read ALL of my comments... students don’t have the SAME rights as adults...
Your original statement was: "minors do not have rights in a democracy", followed by: "children do NOT have rights. Sorry to be so blunt, it it’s true."
After myself and others pointed out this is fallacious -- minors have most of the rights that adults do, and in fact have certain additional rights that adults lack -- you're backing off that extreme position, but still not acknowledging that minors have privacy protections just like adults do, and, in fact in many nations, have
more legal right to privacy than adults.
The issue you're conflating concerns
abrogation of rights. If an adult consents to having their phone searched, they've abrogated their right to privacy. If they consent to having their child's phone searched, this is true as well. However, the right still exists; it simply isn't being
violated because of the consent given.