Some software costs money. Some software is free. Some software is free, with an upsell that you might or might not pay for. And some software has a negative price: not only do you not pay for it, but someone third party is paid to try to get you to install it, often on a per-install basis. Common examples include:
This category of
Ahhh I see, so you're making roughly the same distinction of "hidden revenue streams".
This post is a container for my short-form writing. See this post for meta-level discussion about shortform as an upcoming site feature.