The app helps, but common sense needs to be a factor also.. From my own personal experience I was going to fly in a few locations across town while visiting my Wifes family, who all live very near a smaller regional airport.
After contacting the control tower and chatting with them about my flights, I found that.
A - In one location, off to the side from any approach, but closer to the airport the DJI app wouldn't let me get above 40 feet. To be fair, I was only barely outside the red circle so this wasn't a huge surprise.
B - The real surprise came at another location on the other side of the airport, where I'd have never even attempted to fly as it's on an approach path to the runway and CONSTANTLY has small planes buzzing the treetops overhead.. Here the DJI app showed me easily outside of the red circle, and would have let me fly anywhere I wanted. I only checked out of curiosity, I'd have been scared to fly there due to all of the small plane traffic.
But it sure would have let me do it.