Better mental health care, better education, more strict gun laws. It took 30 seconds to think of solutions other than a surveillance state all of which also are less susceptible to abuse and misuse by single individuals with access to a wide ranging surveillance system.

Most mass shooters have not at all been concerned about getting caught, just doing as much damage as possible before getting killed it caught. Unless the idea is to start with "pre-crime" levels of surveillance, in which case big oof.