But it's always somebody else's fault.

didn't come to a stop entering a circle

??? That's...not a thing. On roundabouts, you give way to vehicles already on the roundabout. If there's no one for you to give way to, you don't stop. Clips 1, 2, and 3 all clearly show the postie entering the roundabout long before the car driver did, and then being struck in the side by the car.

I don't know for sure what the law is where you are, but I had a quick look at Danish roundabout laws and as far as I can tell the laws in this respect are identical.

Clip 4 and 5 are unclear, but seem likely to be signalised intersections, where the postie is going straight and a car is turning right across their path. In that circumstance, there are three common possibilities:

1. The car had a green right turn arrow. The postie had a red light. Postie is in the wrong (though arguably the car is also liable for driving without due care: even if you have right of way, that's not a legal excuse to hit someone who failed to correctly give way to you).
2. Both car and postie had a green "go" light. Car had no turning light. Neither red nor green. In this case, car is allowed to turn right, but only after giving way to anyone going straight or turning left from the oncoming lane. Car failed to give way.
3. Car had a red right turn arrow. Postie had green go light.

Considering they shared the video, 2 is overwhelmingly more likely. 2 also rules out anyone blatantly running a red light, which is certainly less common than failing to give way when you were allowed to go so long as you give way, though it's by no means uncommon.

Clip 6 is also unclear, but seems to be an uncontrolled T-intersection where postie is on the main/continuing road and the car is on the other leg. Vehicles on the side street are required to give way to vehicles on the continuing road, which car failed to do.

Legit. Its like Monty. If you hit that thing you need to have an investigative team go right up your colon because it requires a level of ignorance and obliviousness that should bar you from holding a license

Improving driving standards and increasing punishments won't fix this. Drivers will always make mistakes. Cars and trucks are unsafe at any speed and need to be separated from more vulnerable road users.

To play devils advocate- they need more dark spots. Against the sunlight up some hills, they basically become invisible.

Maybe stop hitting them with your car then!