Understanding ground to earth and neutral, trying to make my home safe
I suggest that if you are really concerned about electrical safety, hire a professional to look at your electrical installation.

You going around with a tester screwdriver and seeing it light up MEANS NOTHING as these testers are very sensitive and light up at the smallest of signals. Capacitive coupling between wires is enough to make it light up. That means an unconnected wire (which is perfectly safe to touch, it is not connected to anything) running next to a live wire is already enough to make the tester light up when you test the unconnected wire.

Also nearly all power adapters and phone chargers can make that tester light up while they're perfectly safe to use. Power adapter also have some capacitive coupling to the mains which these devices need to prevent them from disturbing other devices.