Nothing is free in the world. Wikipedia is living of donations, same for most of linux distros.

Google and Facebook are living thanks to the nice value of your data and also thanks to your free contributions.

Yes, you contributed to Google Maps for free, you did get nothing for the time you spent on it, nobody know that you did this work, you get no acknowledgement except maybe an email for which the only goal is to make you do more free work.

All visitors coming to Google Maps are thanking Google for the work you've done. And after all this free hard work, you are still paying for the use of their product with your data.