Yes, on the surface saying "I'm sorry" is easy and trivial. But once said it implies ownership for the person saying it. For Israel to own this event would be catastrophic, as it would require a big change of policy with respect to Gaza an area run by terrorists. You can spin it all you want ... they are killers. What about the ruturn of Gilad Shalit? That too, would be just as easy as saying sorry.
Donald Trump: Israeli settlement construction in West Bank should 'keep going' (Haaretz)
from the article: The Israeli government's inability to say 'sorry'