Is a proven fact that results which are related to the individual user, that is, that takes into account his search history and the place where he is, are more relevant than non-personalized results.
It can also be described like this: How we get the localized version of the same concept correctly (financial institution, sport, etc.). [...] However, the same query can mean entirely different things in different countries. For example, [Côte d'Or] is a geographic region in France – but it is a large chocolate manufacturer in neighboring French-speaking Belgium; and yes, we get that right too. (Google Blog)
Some watchers have critized local searches becauses they feel that local resources are against global information. Your own experience shows it when looking for pages in your own language and finding difficult to have them because you are in a foreign country. For Google algorithms, the most relevant results are from the country you are in, with language matters involved.
[...] Personalised/local results [...]