The point is it's a frame of reference. The claim is that 30% is ridiculous. Why? Based on other comments in the discussion, it sounds in the same ballpark to other online stores, ones without Apple's anticompetitive pressure.

If that's the case, it sounds like a very lucrative market, so competition should bring that number down if it's so profitable.

Again, this is a separate question from Apple's anticompetitive behavior, it's solely about whether a 30% cut is itself reasonable or outrageous.