There are mirrors that are one way. From one side you can see through it. From the other side it’s a mirror. Someone should come up with glass that’s one way bullet. One side is bullet proof. The good guy side isn’t.
They make this glass. Or rather, they made this glass. I saw it demonstrated in the 1990s. It was designed for armored cars, so the body guards could fire out. One thing though, one shot from the inside, allowed outside shots to penetrate. I have no idea if anyone actually bought it.
Back in the late 1960’s, the NYPD organized their “Stakeout Unit” to deal with a wave of robberies. They would lay in wait at stores which were at high risk of being hit, and take out the robbers. They were very successful. Unfortunately, the number of robbers they put in the morgue caused the politicians to decide to disband them.
https://www.youtube.com/watch?v=Tempcmb5hZU
I can just imagine the uproar if such a unit was used today.