People expect it because it's the expectation they are told to have. When you see "1 of 200,000,000 results" you think you can scroll through all of them.

If Google would say "1 of over 1000 results" and cut off at page 10 of 100 results with a nice message saying "please refine your search query if you haven't found what you're looking for," nobody here would be complaining.