The way they made it sound seemed like they built a new solution for the maps. Them using OSM over Google Maps doesn't seem like it is too much of a big deal due to Lyft's limited presence.
In some sense OSM is "just" the database — what things exist and where are those things.
A mapping product like Google/Apple Maps includes a lot more functionality that often gets taken for granted.
For instance:
- A geocoding search engine to find places by name, address, or description
- navigational directions
- tiling and other data distribution (which is both software and hardware)
- styling and UI
There is a huge variety of open source options for this functionality, but it's hardly a plug and play thing, and quality varies wildly. Putting it all together is no small feat.
Disclaimer: I work on Headway (https://about.maps.earth) which is trying to make this kind of thing easier.