incorrect: maps was an apple app that use google maps service. So it was apple that stopped improving maps on Ios
Do you have evidence of this? I find the history of this fascinating and have my own theories (that I've posted elsewhere), but this is a pretty definitive statement that isn't the way I imagined things going down.
For instance, when Google launched turn-by-turn navigation for Android they said that it'd be available on the iPhone as well before long. That never happened.