Facebook collects a lot of data from people and admits it. And it also collects data which isn't admitted. And Google does too. As for Microsoft, I don't know. But I do know that Windows has features that send data about the user.
Android is very different from the GNU/Linux operating system because it contains very little of GNU. Indeed, just about the only component in common between Android and GNU/Linux is Linux, the kernel.
Also, because schools must teach the spirit of goodwill, the habit of helping others around you, every class should have this rule: students, if you bring software to class you may not keep it for yourself.
Sharing is good, and with digital technology, sharing is easy.
Software patents are dangerous to software developers because they impose monopolies on software ideas.
Free software is software that respects your freedom and the social solidarity of your community. So it's free as in freedom.
In essence, Chrome OS is the GNU/Linux operating system. However, it is delivered without the usual applications, and rigged up to impede and discourage installing applications.
Proprietary software tends to have malicious features. The point is with a proprietary program, when the users don't have the source code, we can never tell. So you must consider every proprietary program as potential malware.
If you use a proprietary program or somebody else's web server, you're defenceless. You're putty in the hands of whoever developed that software.
Proprietary software is an injustice.