I went on a forum in 2013 to figure out how to plan a route other than what Maps was giving me. Do you know what people said? “Why would you want to do that? Apple knows the best route, just follow what they say!” Even if it meant bringing me through NYC and over expensive bridges 
It can be told to avoid tolls, but you might not like what it does. A sensible behaviour for it might be to let you know that there was a toll and ask whether you want to find an alternative. Then it could tell someone that they could choose an alternative, it would cost $15 less but would involve an extra 20 minutes driving. The great thing about AI is that people can determine what response the AI should give and then the AI is built to give the responses.