There are ongoing discussions regarding this on their github.
Some parts of the world have traffic data freely available, in other parts you may need to pay for it. For example, see the list compiled by GraphHopper here: https://github.com/graphhopper/open-traffic-collection?tab=readme-ov-file
On the CoMaps github there are privacy concerns being brought up with live traffic data collection. Some want extra privacy where no telemetry is ever collected. Some want to be able to provide an API key for traffic data. Some want an opt-in feature with a focus on privacy protections. For example, geofencing to protect home locations, stripping out data near the starting location and end destination of any trip, stripping out IP information, only counting average speeds on certain tiles of the map, etc.
In the end I’m hoping for CoMaps to pull through with a live traffic option that also has strong privacy protections in place.
This reminds me of the Free Law Project, where there’s a large network of people that upload court documents for anything that they’ve paid for initial access to.