They most certainly do. I got a quote from Google for commercial maps use a few weeks ago. 17.5k/yr an up. Mapbox seems like a good alternative for serious web mapping. Google Maps is still pretty week in B2B type mapping though. Esri is the real competitor here.

Only 17.5k/yr? You got off easy! Our first quote at $work was 6 figures, though we ended up settling on a figure more than yours and less than $100k/yr. We've now switched to OSM + MapQuest open tiles + leaflet and couldn't be happier with the result.

They do compete with Google Map tiles. And so far that seems to be their biggest factor of financial income, at least looking from the outside.