What if the car had a fold down rear seat and it was open to the car interior? As long the the two kids could crawl out via the car interior what's wrong? I'm not saying that was the case in this situation but I'm not sure it would be much different than a station wagon for some cars.
If that were the case then it wouldn't be called a "trunk" of the car in the article.
It sounds like it was a small, compact car with a standard, enclosed trunk. If it was as you describe it, then it wouldn't even be worthy as a news item.
Rumble seat?