1. I don't see how you participate much more easily without your knowledge. Phones are everywhere, record video, audio, etc. You think because it's not pointed at you on someone's face you aren't participating?

2. You don't think retail stores are already doing this anyway with their security cameras?

Google search for "Retail store video analytics".

(http://blog.nrf.com/2013/06/13/how-retailers-can-drive-perfo... for example, has some real life examples of what various stores are doing)

They don't make any pretense that it's for training purposes.

I guess i'm here to break it to you that you are already participating without your knowledge, everywhere, glass or not.

The only difference is that glass gives you some inkling it is happening.