I also think they didn't comprehend that Iran has prepared for this. I don't mean bracing up due to recent threats. I mean, the US has been threatening their very existence for such a very long time.
They are prepared, they have strategies, they don't use expensive tech where something else will do, & they have made themselves intimately familiar with their enemies' capabilities. What else would anyone expect them to do?
They knew we intended to come for them eventually.