The complaint against Google isn't about displaying ads in Google for Education, it's about violating users' trust, as defined in their contracts. Google promised not to mine users' data and they went ahead and did it anyway. Users noticed that their data was being used for targeting ads, based on their Google for Education data, elsewhere on the internet. Google follows you and watches you everywhere, whether ads are displayed or not. If you want a small demonstration of how pervasive, persistent, and intrusive Google's surveillance software is, you can try two tricks using Firefox web browser:
#2 - Turn off local storage (Local Shared Objects) in Flash Player: https://www.macromedia.com/support/documentation/en/flashplayer/help/help02.html You'll see error messages every time a web page tries to store local data on your computer. Google uses this (AKA "Flash cookies") to identify users who may be blocking surveillance by other means, e.g. NoScript.
The latest development is to use HTML5 to perform Canvas fingerprinting: http://en.wikipedia.org/wiki/Canvas_fingerprinting To get around users who block both Flash and JS surveillance. The only way I know of to block this so far is to use the TOR browser bundle: https://www.torproject.org/projects/torbrowser.html.en
N.B. Using TOR in some countries may alert the interest of their security agencies and can have you put on secret extra-judicial watch lists as a radical, extremist, or person of interest, and can even contribute to you being put on so called "no-fly" lists: https://firstlook.org/theintercept/article/2014/07/23/blacklisted/
Simply put, there are plenty of legitimate and reasonable objections for learners to raise against being forced to use web services from Google, M$, Yahoo!, DropBox, etc.