(i) http://www.t-mobile.com/offer/music-freedom-list.html This is a large enough list that I wouldn't worry about anti-competitiveness. It is still them vs. everyone else, but looking at the list right now, the barriers to entry cannot be that high, which means any anti-competitive effect cannot be that high either. I and most others in my income category (college undergrads) are willing to accept this in order to have free music streaming.
(ii) Facebook (in some parts of the developing world) is a slightly different issue, and not necessarily one that I agree with. Still, zero rating popular websites in the developing world seems to be win-win-win for consumers, carriers, and content providers, and ignoring market forces is simply not a solution. Especially if the target demographic simply cannot afford to pay for data - this is an entirely different market and I don't have the experience to form an opinion on this. Edited my original post to remove Facebook.
(iii) Let's assume all paid traffic should be treated equally. And to keep things fair to paying customers, paid traffic should be prioritized over free traffic. I'm willing to bet this already happens indirectly - by lowering the music quality when the network is congested.
But what if I have Spotify Premium - I (indirectly) pay for my traffic, so why should your maps app be any more important?
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Obviously there are tough questions here, and a "one size fits all" net neutrality approach for wireless and broadband might not be the best solution.
If wireless was as cheap and fast as broadband, I would be all for net neutrality on wireless. But it's not. They are different 'products' in economic terms (even if they have a similar end result and "feel the same"), and I think it's therefore okay for policies that govern them to be different.