Because it takes times to crawl and index those links. Many times, links too get deleted. All of this is a continuous activity so you never see all backinks.
The main reason Google will never show all backlinks is that if they did, I would find the backlinks of all my competitors and get them from the same sites so that I could outrank them.
Google doesn't show all of the backlinks in their search engine. There is no tool that shows all backlinks to a page. You can find more through Yahoo!. Type in link:http://www.website.com and you will see more links. If you have Google Webmaster tools, you will be able to see more in there as well.
Your backlinks will only be shown in google when they are indexed. You can use a backlink tool like backlinkwatch.com to show all your backlinks.
Nobody really shows all the backlinks they find. If you really want a good picture of backlinks sign up for Google webmaster tools. It shows more than most things, but I still would argue it doesn't even show close to all the links it has found.
Google tends to shower less backlinks than Yahoo. And the ones they do show are usually higher quality.
I am not sure what you are trying to say exactly, but not all backlinks get indexed and are visible in link checking tools.
From what I've learned, Google shows only 10% of the total backlinks, and most of those listed sites have high PageRank value.
You can try the backlinks query yahoo, google seems to have improved his webmaster tools, it is said to accurately view the external links
Google webmaster tools show very few backlinks... Links which are displayed has nothing to do with their importance. It randomly display some backlinks On the other hand, with the link command you can see latest backlinks of your website. For the approximate backlinks count, use Yahoo! Siteexplorer. http://siteexplorer.search.yahoo.com/
Really? This is interesting to me because by Google Webmaster tools shows more than any other service I have found.
as far as indexing the site's page is concerned google is most fastest.while creating backlinks of your website from other sites bing is more fast.