google search

It has to do with word/name association, how a brand is taken to mean a product, even if it was not the first this is an old example but bear with me it is like old fotocopiers were sometimes called Xerox machines even if they were from a different company. The thing with the name is that it is easy to pronounce, easy to remember and is unique to the internet, googling is much quicker to say then - doing an internet search or searching for x on (search engine). There are several other search engines that don't get the attention even though they are just as good. If you think that a search engine is basically a pointer, it is like asking directions, if you ask 10 people directions to something like a monument probably 9 will all give you the same directions, if you ask for something smaller less well known then you will get totally different directions. The same applies here, so for big things most search engines will have the same results.