Besides these linguistic difficulties, there are field limitations. I was recently looking for an author whose last name was Diamond. Clearly, some of these databases had space limitations. Barbara Lee takes up one more space than Barbaralee. The spelling of Spielvogel is up for grabs and note the fact that a period after the first name causes a separate index listing.
Names have different conventions depending upon the person's country of origin.
Take Spanish names, for example. If you are looking for Jose Garcia Diego, you should probably check the Named Person field under both Garcia Diego, Jose and Diego, Jose Garcia. You may know that the Spanish convention, generally speaking, is to consider Garcia Diego the last name. The indexer may not know the same thing you do. Thus, it is a wise searcher who overcompensates and uses both possibilities.