RaceChrono currently uses Google Maps/Satellite Imagery as the background on Android. On iOS it seems to use Apple's map service (I don't own the iOS app). They issue is, free mapping services like Google/Apple update slowly, especially in rural regions which happens to be where most race tracks are found. Depending on where you are it can take years before the new local track gets covered by Google.
Since different map services update at different schedule, if RaceChrono supports different services, the chance of at least one of them updating in time to cover the track would be much greater than relying on Google/Apple alone. Some countries/regions even have local mapping services that update much more frequently than global ones.
There is no need for RaceChrono to manage different map sources for its user base across the globe. Simply add a custom Web Map Tile Service option with user-provided URL (plus some metadata like image size, image type/MIME, Y-axis inversion toggle, zoom level limit), and the users should be able to figure out the rest.
Note that accessing Google tiles directly with custom URL is against their ToS. Make sure custom URLs containing Google domains are rejected.
