Why is attendance SO low at Internations events? (Munich)

I see that several people sign up for events and yet only about 1/3 of the people actually show up?

Can someone help me to understand why this is please.

And please don't say that people have busy lives and/or they have many choices of things to do. Having lived in London / NYC and other US cities where there is even more of an abundance of activities and things to do, yet attendance there was considerably higher than here in Munich.

This seems to be either a Munich/German/Internations thing.

Would love to understand the thinking and mindset here.