Good behavior or bad behavior? (Vienna)

Reliability or unreliability?
Good behavior or bad behavior?
Behaviors in Central Europe - or am I wrong?

To my surprise, about 40% of the registered persons do not come to the event.

This fact I will probably never understand. In our society, in which I grew up, it is good manners to attend an event if you have registered.
Anything else is unacceptable in my view.
Not only the organizers but also visitors expect that registered persons appear.

In this case, no more than a click of Mous would needs to officially sign out. Is that too much?

I must be about more than surprised.

Here I will have no right to, and I hope it takes me no evil, that I have expressed. But this fact is I have long been on the liver.

Sorry my bad english.

My best wishes to All!
Richard