I once asked this question to the android developer in my company. And they said the google does not charge for such API requests.I think this is misconception of many developers and journalists. The API document mentions that your use of API should be under fair use for you to use it as FREE. And if you go beyond that usage, you have to pay like other enterprise users.
Here service request means you choosing a location on the map and then zooming in or out or making a flag on the location. Or even making the direction from one to another location. All these requests are counted towards API requests. So for free version of API access limits you to making 10K calls a day or more depending on the category of your app. Higher calls require you to use enterprise or business access.
Only free calls you can make through API without any money are as a consumer inside the app. If you choose to use API in your program, at some point in future if the app scales, you have to pay. There are countless number of services that are mushroomed on google's map service. Be it google maps, earth, moon etc. Lot of companies making use of google's data. Some companies also make use of the openstreetmap data if google's API restriction limits their use.