Actually, if students are dependents of their parents for tax purposes, colleges are allowed to disclose most info about the student to the parents, including trips to the emergency room for alcohol poisoning, etc. But the colleges are not required to initiate such disclosures, and many have a policy of not doing so, for liability reasons, i.e. if they have a policy of doing so, and then miss one that turns out to have tragic results, the parents who didn't get important info will have grounds to sue.
Actually, they're not. My daughter is in college and in the parent orientation, they told us that any child over 18 can't be discussed. They specifically mentioned alcohol poisoning. Her school made the policy that if the child could talk, then they will follow their direction. If they can't, then they will call the parents. My husband is a college professor and he can't tell parents anything. But again, he has developed ways that he can share info if parents and students come in to talk. It's usually when Johnny knows he's not doing well and it's the professor's fault and he sics parents on him. Smart profs are prepared, though, and can stealthily convey info.