I don't see how they have a monopoly on the search engine market. It is definitely the most popular and probably the best search engine, but there is definitely no limit on other adequate alternatives. A monopoly occurs when a company controls a product or service significantly enough to significantly control the terms people must follow access it. Google hardly does this. Most people might choose them, but they don't need to in order to access a search engine. For example, if tomorrow Google decided to start charging a buck a search, 99.9% of their users would instantly switch search engines with very little ill effects.