Because MOST people that have suggestions that are different from the app DON'T know what they're talking about, or are ignorant to real-time conditions like tr

Because MOST people that have suggestions that are different from the app DON'T know what they're talking about, or are ignorant to real-time conditions like traffic and accidents that the app would take into account. Obviously in your example it should be trivial to just do what you said, but ignoring the human and following the app is a safe rule of thumb 99% of the time, and not increase one's cognitive decision load. Also a u-turn in a two-way street is always safe, until the one time it isn't, and you get a ticket from a cop you don't notice somewhere on the horizon (happened to me once)