You can't really infer hat some one is driving from the device's speed. GPS won't tell if a person is sitting in a drivers seat or in a passenger seat or on a train or some other vehicle. Also the GPS radio would need to be on whenever the device were in operation to know the device's speed which could contribute to a shorter battery life.
Also while laws vary from one jurisdiction to another some jurisdictions allow texting and driving for emergency scenarios.
It takes all the running you can do to stay in one place.If you want to get somewhere else,you must try to run at least twice as fast as that.