According to their website, they sell an SDK to business partners and allow end users to make donations.
Free and Open Source Software
If it's free and open source and it's also software, it can be discussed here. Subcommunity of Technology.
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Specifically this section:
Why is Magic Earth free? What is the business model?
Magic Earth is free for all our end-users but we also have a paid Magic Earth SDK for business partners. For instance Selectric.de (a supplier for navigation solutions for ambulances and fire trucks), Smarter AI (developing ADAS systems) or Absolute Cycling (using the platform on bicycles). For more info on the SDK, you can check magiclane.com.
I didn't see the FAQ, thanks!
For public transport nly (I mean, not live traffic) you have the open source Transportr on Android at least (on F-Droid for instance)
Thanks for the suggestion! I knew it but my country isn't in it :'( I could get involved to add it though...