Now, whether it is better for many innocent people to die so that a terrorist doesn't live is up to you. You asked for a reason, not a good one.
It certainly isn't one in ten million "evil" doctors. Consider that you might be underestimating the likelihood because you want people to be organ donors. I'd say the main reason the official respectable stance is that you'll never have your organs harvested when you would live is that people want more organ donors so they fall for whatever belief helps make it happen.
I certainly couldn't care less what people might do with my body once I'm dead. Burn it, bury it, ignore it, worship it -- whatever floats their boat.
So the chart is exactly as is stated.
In opt-in countries you have to contact authorities to opt-in and in opt-out countries you have to contact authorities to opt-out.
The author has a moral position made clear early in the article, when saying that more than 99% "failed to opt-out".
No they didn't fail to do anything. They either chose not to, or did care enough about the subject matter to make a choice.