According to liberal logic, you can't have a panic button, without something justifying a panic.
Public school teachers are , for the most part, people who are too irresponsible, stupid, or self aggrandizing to get by in the private sector. They are "useless know it alls" who mostly enjoy the idea of being in an environment where people have no choice but to treat them with deference, even if they probably don't deserve it. The only person in the last 20 years who intentionally and stubbornly continued to condescend to me after it was obvious to everyone in the room that I knew more about the topic than she did, was a public school teacher.
Those people can't do, so instead they teach.
Give them a bunch of panic buttons, and everything to them will seem like a panic. Child raises his voice? Panic. Child refuses to return to their seat with the proper speed or alacrity? Panic. Child adamantly disagrees with the political position of the teacher? Panic. Over time the Marietta Ga. police department will learn not to take the teacher 'panic's so seriously, because the teachers themselves aren't serious.
So instead they'll come up with a bunch of zero tolerance rules that even public school teachers can understand. They will spell out with meticulous precision which circumstances justify a panic and which don't. And the value added of the whole 'panic button' concept will be reduced to zero. Might as well just tell them to carry a cell phone.
The fact is, even with gun free school zone laws ensuring the defenselessness of our children and education employees, school shootings happen very rarely. Far too rarely to justify a 'panic button' system. but the good citizens of Marietta will no doubt figure that out.