Earlier quoted context omitted.
Why should they offer a free maps service? They are a business with shareholder responsibilities, not a charity, and maps must cost them a ton of money to operate.
You are correct. The reverse is true too, why should contribute data to their maps service for free? I've done lot of work to add and correct roads, update business info and addresses in my area. If they want to fill the map with ads they have that right - but when they drive me (and people like me) away, their product will suffer.
I actually want the ads too although I want them 100x better than they are and I'm sure Google like Amazon will fail for a while at curating the fake stuff. In an ideal world they'd have inventory and menus of every store so I could search for "pizza with avocados open now" or "1/4inch wrench" and it could tell me exactly where I can get them right now.