Well the red and white bar on the bottom of the tail rotor is literally called the stinger. It’s there to protect the tail rotor from striking objects. It’s effect is limited for obvious reasons.
When doing full downs, which is an auto all the way to the ground, you generally try to level the ship before striking the tail. I’ve hit the tail on the ground before by not leveling at the right time and had no damage to the aircraft. But if you hit hard enough it’s an easy way to rip the tail off the ship. It’s common when learning the full down auto. And it doesn’t take much. Which is why it’s considered an advanced maneuver and not usually taught to private students.
Private students are generally taught to terminate the auto a few feet in the air. Generally 1.5 to 2 times of the length of the ship. That’s enough to survive the impact. The bird will likely be a total loss but the occupants will walk/limp away. Not saying I agree with the practice it’s just what is common for civilian students.
Once you hit commercial or CFI you start doing them all the way to the ground. And quickly it’s and elbows at the end of the maneuver so you need to be comfortable flying the bird that a private level student isn’t going to be. Striking the tail and not is literally the difference of milliseconds.