Ratings based on unrealistic expectations
The safest speed on the highway is to follow current traffic flow speeds, which sometimes are 5-10 miles over the speed limit. Driving much slower than current highway traffic, even when on the right lane, is actually proven to be much more dangerous, and this app does not account for that.
When driving in the city, you are constantly faced with wildlife that abruptly run in front of your vehicle, or pedestrians who cross the street but not where crosswalks are placed, so you are often forced to quickly brake. This app does not account for that either, and apparently would rather that you hit said wild life or pedestrians than to brake quickly.
Overall, this app is meant to be a means for the insurance company to hike up your premium rates by attempting to deem unrealistic driving conditions as the norm.