Read that again. If you make a classifieds website but charge businesses to list, it's a violation of the free Maps API TOS and you need to purchase an Enterprise license. Enterprise licenses start at 5 figures/annum for low-volume usage.
This is not some abstract ideological nitpick. Google has ramped up its attempts to monetize Maps ever since they introduced quotas a couple years back, and they are actively pursuing businesses to force them to buy an Enterprise license. So there is a very real risk that you could be targeted if you embed Google Maps, especially if your website gets big. This is no doubt one reason why companies like Foursquare, Craigslist, etc. use OpenStreetMap rather than Google Maps.