We're "in the country" just barely, and regularly see similar tracks around our place...someone took out the guard rail of the bridge over our creek a couple of years ago...but mostly, they just mow down our mailbox.
This year I've replaced it three times. This last time, they drove right into it, snapped the 4 x 4 post off at the ground, and flattened everything else. So, I decided instead of killing my back one more time digging a post-hole, we set the 4 x 4 into a huge flowerpot, filled with 2 1/2 bags of cement mix, with some nice, heavy rocks set into the top. If they try it again, they won't have a "front end" to worry about.
Of course, the next week they just flattened the box with a sledgehammer, leaving our nice flowerpot full-concrete untouched. So, we got a cheap plastic mailbox and decided they can bash it all they want...it'll just spring back into shape!