It’s a guess without any empirical evidence whatsoever. However, the only reason why you believe it “contradicts evidence” is because nobody ever talks about ICE encounters that go down peacefully. People only ever talk about and post about ICE encounters that are outrageous. So all the encounters you have ever heard of will be ones where someone gets wrongfully arrested/beaten up by agents/etc.

When I saw them, they were checking everyone and arrested 0 people in the time I observed them.