Disagree on that. It is the freemium model that's used. Specifically enterprise tiers for the vast majority of OSS.
There is a crucial subsection of OSS used within companies but those often come with support contracts and branding which is what you're referring to with Google, but a far cry from "most".
No, like, how many companies are paying support contracts for Nginx, anything you npm install, anything their engineers 'brew install'. Some of these might have support contracts that you can buy, but that's not used in the vast majority of cases.
I really do think you're not seeing the forest through the trees here.
There is a crucial subsection of OSS used within companies but those often come with support contracts and branding which is what you're referring to with Google, but a far cry from "most".