Google isn't the best search engine...There is another called Copernic...It takes from ALL of the search engines. Also Google isn't good for kids. Bing you can make it much safer, more settings. Bing and Copernic work best for me...Yahoo is pretty good too. I hate Google. It'll bring up things not related to what I typed in.
Google makes its money by tracking us. This is no secret, they track just about every site you visit (as most sites use google-analytics to give them information about who's visiting their site. Convenient for google). Google "uses this information to display better ads relative to you". who knows what else they do with the information.
Regardless their search engine is second to none. But there is no reason to give trustworthiness and privacy anything higher than unsatisfactory.