It's tough to say for sure what they are currently manipulating about your experience because they have so many vectors they can use. But I think the issue is that the amount of data they are collecting goes beyond the "lets improve the experience" argument. For example google "reads" all of your gmail[0]. They might want to do this for better targeted advertising which isn't nefarious (though it does exchange your privacy for the sake of their bottom line), but I think you or me would prefer they didn't in favor of less precise advertising. Same goes for your search results.
True they have the right to use your data since you used their apps, but as far as search/email goes I don't think it's too far off to suggest you don't have that many alternatives- and you probably don't have any reasonable alternatives that don't read your emails or track your search. In situations like this I think a lot of people would prefer their government step in and have a large amount of oversight into their business practices so thats probably where all the sentiment is coming from.
[0] https://www.makeuseof.com/tag/google-third-party-apps-read-g...
