No kidding. Remember the surprise afternoon snowstorm a couple or three winters ago, no pre-salting and the roads were too choked with cars going nowhere for the plows to move.
JUST in time to turn the afternoon commute heckrides. I was home safe and sound and laughing out the window until my sister called me with an SOS, snowed into a parking lot. Something like 6 hours for a 45 mile round trip to rescue her and her cat, General Chow. Never did figure out why she had her cat with her.
And THAT wasn't a SHTF scenario, just a bad snowstorm with perfect timing.
To move anywhere in a lawless world with millions of others trying to do the same thing you'll have to go over (flying) or through (crushing) the others. Maybe a nimble dirt bike rider, until someone shoots you for the bike.