The smaller screen space would show up in mobile revenue (which is not broken out by Google, so we don't actually know whether that's happening), but not in mobile CPC. CPC is "cost-per-click", so if fewer ads are shown per page, there will be fewer clicks, which might even drive CPC up if only the highest-quality ads are shown. CPC as a metric is usually used as a proxy of the value of a Google ad to an advertiser; because of the auction system, an advertiser bids only what the ad is worth to them.

Facebook has a very different ad strategy on both desktop and mobile. They target brand awareness much more than purchasing intent. As a user, I'm starting to see Facebook ads in my newsfeed of sites I never searched for or Liked on Facebook; AFAICT, they're using cookie data from the advertiser's website itself to inject the ad into your stream, so that you're reminded of the product on a regular basis. I can see why this would be worth a lot to the advertiser (targeted brand advertising!), but as a user, it is creepy and annoying as hell.