If all apps had equal access to zero rating, then that'd be one thing. If I can just go to some site and pay for traffic to my site, cool. But is that reality?
On top of that, I would be surprised if some carriers are not just doing it as a marketing service. In Guatemala, I see huge billboards saying you don't need to pay anything to use Facebook, Whatsapp and some others. If you have an active line (meaning you've spent a dollar in a month or two or something low), you're set to use them.
Even promotion like that is somewhat anticompetitive if there's no way for other parties to let users know.
On top of that, I would be surprised if some carriers are not just doing it as a marketing service. In Guatemala, I see huge billboards saying you don't need to pay anything to use Facebook, Whatsapp and some others. If you have an active line (meaning you've spent a dollar in a month or two or something low), you're set to use them.
Even promotion like that is somewhat anticompetitive if there's no way for other parties to let users know.