Woman charged with unintentional arson after cigarette allegedly started fire on Greek Island

So, why is this in the news at all?

Because she allegedly didn't stub it out thoroughly.

But is it an unintentional oxymoron?

Headline's in English, story's in English, the phrase is an oxymoron in English.

Obviously just bad translations into your language.

Also, Greece is not bound to your understanding of anything :)

admitted she had thrown a cigarette that had ignited one of [the five] fronts

So, why is this in the news at all?

In the good old times people were used to stub them out thoroughly.

arson, n. The crime of deliberately starting a fire with intent to cause damage.

The dictionary confirms my understanding that "unintentional arson" is a contradiction in terms. We must therefore find the defendant not guilty.