Sorry if that was a bit of a rant: illegal no.
The best example is phone number portability. By legally forcing all mobile carriers to offer phone number portability, users can switch between carriers without losing their existing phone number. This reduces lock-in to providers, and encourages them to compete on price and service instead. No sane carrier would offer phone number portability without being required to, since it only helps customers who move away.
FTC has decided that Google isn't unfairly using its popular products to prop up unpopular ones so far, and I think Bing Maps and Apple Maps are close enough substitutes to not consider Google Maps a monopoly. Also, ridesharing seems to be booked mostly via custom apps, not from general map apps. But if Google Maps really was the only serious option for looking up rides, then I would see the benefit to consumers to requiring Google to integrate all major ridesharing services.