If you're sitting in Atlanta, it makes sense that when you Google "Hair Dressers" you are probably most interested in services near to you. It doesn't do you any good to know "Jimmy's Haircut Shop" in Vancouver BC doesn't require an appointment; you need to know who in your area can cut your hair.
Google's searches have several mechanisms in place to help with this. For example, an American will automatically be directed to Google.com when they navigate to Google. Here in Canada, you get sent to Google.ca, and in Jolly Old England, you go to Google.co.uk. Each is designed to help users find search results most likely relevant to them. Canadians are more likely to see Canadian sites ranked higher.
However, this "helping" can effectively mean people in some countries are blind about what occurs elsewhere in the world. Many people do not look beyond the first page of results when they have performed a Google search. Hence the intensely competitive "Search Engine Optimization" industry that works hard to ensure sites are ranked highest. What this all means for a researcher new to the internet or unaware of the perils is that depending on where you live, Google might not point you to the same resources. This is especially the case if you are trying to research another region.
For example: the Google search for "england history" on the US, UK and Canadian instances of Google all provide 83 000 000 matches.
However, while the page "The History of England" ranks 6th on the UK version of Google, it is ranked 66th on the Canadian and American versions of the search engine, deep enough down that most people wouldn't likely bother to check it out.
If I were interested in the Network in Canadian History & Environment (NiCHE), hosted at niche.uwo.ca, and did a search for "niche", what I found would depend on where I lived:
Google.ca rank: 3rd
Google.com rank: 15th
Google.co.uk rank: 420th (that's the 42nd page!)
The .ca attached to the address means that Google has decided that this page is likely irrelevant to Brits. Now, granted, I should probably refine my search to get beyond the fact that a search for a word like "niche" is a bit ambiguous. But, the important thing to take away here is that Google is vetting what knowledge we find, in many cases without us even being aware of it.
What can we do about it? Probably not very much that will get Google to change their ways. But as responsible researchers and internet users, we should be aware of this. When you're doing research, make sure you don't just accept Google's top 10 suggestions at face value. Try another search engine (there's lots!). And if you're doing research on another country, make sure you try out their version of Google as well as your own.
Technology is great, but we've got to know it's limits.