Walmart et al makes a significant percentage of their money selling positions on the shelf and in-store promotions. The actual margins on product sales aren't nearly as high as a premium products placed within good eye-range at high trafficked parts of the store. Which are almost entirely major global brands.

One way things are 'free' on the internet or at least cheap is by letting the top 10% of products pay extra in a win-win sort of situation, largely subsidizing the wider 90%+.

I think what we're seeing here is Apple spotting a major money maker and saying you're not getting a free pass anymore and have pay like one of the big boys.

That, or Apple has to change their model somehow, which I think would be largely unattractive to their business interests and its worked fine so far with everyone else.