It not a completely one sided relationship. I'm using google maps for free!!! That's HUGE benefit to me. That google makes money from it is irrelevant to me. They're paying me by providing a free service that I get tons of usage out all the time.
It's not free. The cost is the information about where you are and what you're looking for basically at all time.
Yeah, and you made a fix for both yourself, and presumably other people as well. Additionally, some people submit fixes for recognition, too.