I think that it is partially because not enough people care about Snowden. As well, at this point, whenever a new leak comes out, it isn't breaking news; it's just another story in the news cycle. It's the reason why you see people who died (Mandela, Walker, and Monteith) and the Boston Marathon in the top 10 searches. Those events happened much more suddenly and people are going to use Google to find the latest details.

I'll bring up another, more personal experience. Down at Salisbury University in Maryland this year, a girl that I knew from high school and a friend were shot by her ex-boyfriend, who also went to my high school. The friend was killed, the ex committed suicide, and the girl was in critical condition. I was constantly Googling for more details because I wanted to keep up to date with what was going on, as some websites would get more details before others. I had to sort through multiple news sources because the sources either had old information, or, in Daily Mail's case (why the hell they were reporting on an event at a small American college, I don't know), were making up details that weren't being reported anywhere else.

I will admit that I did do a Google search after Paul Walker's death, because in my case, I wasn't familiar with him and all my friends were talking about him on Facebook. On the other hand, I would imagine that people who were more familiar with him were also Googling him because they wanted to get the latest news about what had happened.