Uber and Google Maps
Uber started as a happy Google Maps customer - what could be better than free routing intelligence? By 2016 it was clear: every pickup error, every miscalculated ETA was Uber's customer experience. Maps was the engine; Uber was the wrapper.
Uber spent years and millions trying to escape - tried to acquire Nokia's mapping unit, partnered with TomTom and HERE, eventually built proprietary mapping. By their 2019 IPO they were still paying Google significant sums. Once you're in the trap, escape costs years.