Compare their privacy policies. Otherwise you are right and it's better to use https://yacy.net and SearX.
2) Bing belongs to Microsoft whose primary business is to sell software, not ads, so they are less dependent on collecting user information.
3) If I wanted a search aggregator, I would use a non-US company, for example, Qwant.
2) If it's non-private, it still collects personal data.
3) Or Startpage - HQed in the Netherlands, hides IP address, Anonymous View feature lets you visit results in private, and Google results.
If it was true they would not collect every keystroke on their OS.