As far as the British Columbia list of campgrounds goes.... its terrible. I counted 8 missing campgrounds from one small area where I live. So then I went and looked at another area close by, and again a lot of missing campgounds.
There are so many of these sites out there now, and 99% do not list all the campgrounds.
I still find the best source is contacting tourists offices in the area where your headed.
However it is another website to use if need be.
Soup.