Google's Local Services Ads

Reportedly Google will soon start listening to and recording the calls made to local businesses that it advertises, by people responding to the advertisements.

I have never seen Google's advertisements because I have used few Google services for many, many years, and none for many, many years. I don't know how "local services advertisements" work. Is there something that prevents a person from calling the business's phone number? Is it simply that most people unthinkingly do the simplest thing? </li>