Basic quest on Twitter API user search and the relevance of results -

dear stackoverflowianers, dear twitter-gurus,

this basic question, waiting simple basic answere:

i user search twitter api following url:

https://api.twitter.com/1.1/users/search.json?q=hans%20spitzer&page=1&count=10 

the result looks this: https://snap.apigee.com/1awu22i

now question: why twitter api finds users name "john solo" , screen_name "shock_monster" or e.g. name "vicente durán casas" , screen_name "vicdurcas" , (the best) "swr nachrichten rp" screen_name of "swrnewsrp".

at of search results there no hans spitzer @ inside... why happens or "how make perfect search relevant users"?

thnx. answere in advance!

best regards, ingmar