[danans]

> but choosing to do paid work on your own company's money-making products is not volunteering, it's just regular work but you choose what to work on during 20% of your time.

Disclosure: Google employee, opinion my own.

You are right, but that blog post is using volunteer in the weaker (but nonetheless common) meaning of "someone who raises their hand to do something". 20% time, when done properly, is more of an employee wellness and career/skill building perk. It is like your employer giving you paid time to take a class or training that is related to your job.