This requires people to install the app. That's a failure right there on many levels.
Not only that, but it cannot tell if you are the driver or the passenger. That's failure #2.
Then you get to the fact that this could stop you from making emergency calls. That's questionable and teeters in the "is this even legal?" quesiton range.
It is not just the implementation - the very concept of "if vehicle is moving you cannot use your phone" will ALWAYS be wrong whether it can figure out you are a passenger or not, if the decision is implemented via software.