These extensions do not simply change the default search in the browser. They actively hijack searches on the Google and Bing homepages. Test it yourself in a sandbox.
A user who literally types in Google.com or Bing.com into their browser address bar intends to conduct a search using Google or Bing. Their intention is very clear. It is not to have their search hijacked and taken to a "private" search engine.
They also use Bing to power their search results and ads so Microsoft is still able to collect the user's data.