That will be the case because the search function is looking for the specific word, whereas in the example the specific word is
www.google.com (no spaces causes that issue). Forum software searches are no where near as comprehensive as say a SE search function.
Just the way things are, its possible to update the search abilities of forums but it is major scale programming work and frankly easy for people to learn to search properly using forum search basics not what we call basics now due to SE searchability..
Hope that made sense.
Mike