I think the difference is if Chrome had to stand on its own, it would be even more incentivized to drive traffic to Google for revenue at the expense of user experience.
if people paid for Chrome, Google would have to stop collecting data on its users. Google would much rather have that data than some <$20 fee. If Chrome was its own company, Google's money to be the default search engine would be more than they could earn from selling the browser. Free. Always has. Always will be. wait, that's the other data hoover.
What if google paid it's users directly for their searches.
Sounds like a joke but Bing is actually trying this.