I think most cases for drive-and-go mountain biking probably aim at the casual mountain biker. Someone who just shows up to mountain bike, but otherwise doesn't ride really. People who dip into the woods for an hour or two, then go home.

There are more extreme mountain bikers that vanish off the face of the earth for the whole day, or multiple days.

In any case, nobody expects you to show up to a bike trail on a bike. Does this look like France to you?