"We want to be present on the apps that people already use" How can they not see that an app for traffic lights is clearly the wrong approach? Smart traffic lights are working great in many countries without needing an app for them to work.
This just allows for better traffic flow management by predicting influxes of traffic along long roads.
But, more importantly, it allows traffic planners to analyze popular sources/destinations on the road map. If 90% of cars turn left at a certain traffic light but only because the traffic light before it takes forever to turn green, they can tweak the scheduling to divide traffic more evenly.
The obvious downside, of course, is that this data will quickly show individuals when analyzing patterns in remote areas.
As you said, it's 100% the wrong approach.
Except that's not what they want here. What they want is for the apps that most people already use to add support for this.
The only way to do this effectively is with a planned route, and hence why they need to use an app (the one you're using to navigate/route plan with) and why having the main navigation apps people tend to use (e.g. Waze, GMaps) is desirable.