Bathrooms aren't always closed because of vandalizing. NYC public schools lacked bathrooms and stall doors -- the various heroin epidemics saw to that. Schools closed boys bathrooms and removed stall doors to discourage drug use.

In 1994 my public HS had ONE boys bathroom with no stall doors across from the lunchroom where a public school guard sat and watched. The girls had one on every floor. Had to take a dump? pray no one was in one of three stalls and put your book bag on your lap. My brother went to Brooklyn Tech and had the same missing stall door issue though had more bathrooms.