So if Apple has 70% of the market share, how does Android make up 75%? It can only be less than 30%. Can anyone clarify?

I think that because the sentence includes "of all smartphones sold", the discrepency is describing a shift in market share. Apple could have 70% now, and 75% of all new devices sold now could be Android. They were in the game first, and aggregated a huge market share, but now it is shifting.