If 30% of the price paid is taken by Apple, that means their commission is 43% of the revenue received by the vendor, the hypothetical price you would otherwise pay. A 30% decrease and a 43% increase are the same size; a 30% decrease is much larger than a 30% increase.
Observe: 0.7 * 1.3 = 0.91.
https://i.imgur.com/MBWOc6W.png