Yeah, that’s not really true. What you described is more true about Amazon, which tends to push its own products, particularly on Alexa. And the “more results” functionality likely has to do with mobile search habits, as mobile and tablet now make up close to 60% of all searches.
While I don’t think Google only shows you what they want you to see, they’ve made a number of changes over the past few years that aim to keep users on the search results pages longer. Google makes the majority of its money on advertising; the more time users spend on search results pages, the more opportunity there is to show said users ads, which means more opportunity for users to click on ads.
Google’s claim is that providing answers and information directly in SERPs is providing people with the best experience possible - and that’s somewhat true. But it’s also helping to promote the company’s bottom line. (I suspect we’ll start seeing more advertising in voice searches for that reason.)