Apple is 24% of the smartphone market so anything they do on their their systems only affects that minority portion and isn't denying competitors access to the market.

Android on the other hand has a 74% share of smartphone market so anything they do impacts a majority of the market and could limit others access to the market.

What Apple Maps limitation? You can open Google Maps with Siri now with an ugly work around (https://www.tuaw.com/2012/12/17/how-to-use-google-maps-with-...)

And in iOS 12 any app will be able to provide a Siri shortcut.