I have searched for some services and products in Google like "rent a car" just for example, and generally the first 3 result pages are full (I said full!!) of websites that are not specific for car rentals. They are directories, link pages, or just a piece of text in a newspaper site or some article . Of course, I have refined my searches for something like "sao paulo rent a car", "rio de janeiro rent a car" "other_big_cities rent a car", automobiles, vehicles, and all sort of words we use in portuguese to say the same: "I need to rent a car in that city". So, I try to narrow the focus choosing the local option "Just brazilian pages" (in google. com.br), and I have similar results.
Very few SEOd sites, more than 20 Mi Internet users, I can't believe that I have a market of this size at my hands :rolleyes:
Is it happened in the US market (or other evoluted markets) in the past?

as algorithms shift the type of sites ranking at the top changes. sometimes it appears there is a favoritism toward directories, later times it seems there is a bias toward blogs, other times forums, other times .edu sites, etc etc etc

high search volume might not indicate high value if it is a term that does not convert.

many terms that you would think to be hard are not that hard. sometimes the ones that look easy are a bit hard because they are on pages from exceptionally powerful well trusted high AdWords spending sites such as Amazon.com or some of InterActive corp's travel related sites.