"I'm a passenger" button.

What is the point of the "I'm a passenger" button? I know they have speed restrictions, and I can accept that (as annoying as it is being a genuine passenger and not being able to play) but why add a pop up and button that actually does nothing? I had some hope it was maybe a glitch, but clearly it's just a useless pop up with no actual purpose.

It's probably my biggest gripe with Pokémon GO, the fact my children can now no longer play on our long trips to visit family.