I think it's just a culture thing. German audiences generally do not sing along like North American crowds as a sign of respect. They wait until the performer's done before clapping.
Did she perform "Part of Me"? Literally one of her least known singles here.
+the echo?? It's more of a "classy" award show so i don't get why you would expect the attendees, which are a bunch of 30/40+ year old people, to sing along.