In many rural areas (and not a few non-rural areas) you see highway signs with a bunch of bullet holes in them.
Do people shoot them from a moving vehicle or stop, get out, and use them as target practice?
Feel free to share how it’s done (and I realize the answer could be ‘both’ - perhaps this should have been in IMHO.)
A complete guess is that it would be more of a challenge shooting from a moving vehicle.
In the rural areas, they’re a convenient target to ‘check your sights/scope’. 
As for non-rural areas, my WAG is that it’s just ‘hooligans’.
Missed the ‘edit’ window.
“Hey Clem, pull over here (about a 100 yards from a ‘deer crossing’ sign) I wanna check my scope.” Get out, take a rest thru the open window of the open door, take a couple shots, get back in, check the ‘target’ as you drive by.
At least, that’s how we did it. 
We never stopped, just plugged away while driving.
Hopefully it was the passenger shooting, not the driver, right?
It’s basically the grown-up version of Mailbox Baseball.
We’d bait them first, which is why they called it a feeder road.
You get out about a hundred yards from the sign and aim for the O in the word STOP.
No one ever seems to bother to check what’s downrange of the sign.
A whole bunch of nothing is down range of the ones I’ve allegedly shot at. Just miles and miles of Texas.
I suspect it’s done from the passenger side of moving vehicles. Has to be very loud inside the vehicle. I’ve tried to pay attention and it does seem like they check what’s downrange of the signs around here in Virginia.
Speak for yourself.
I ALWAYS ‘check downrange’. 
Copy that.
Don’t miss with Texas.
Dunno about other road signs, but, when I lived near Bullard, TX, it was out in the deep, deep woods, right off of a highway. A small road, paved, had some sign on it with bullet holes in it. Along came a couple of the locals, one whipped out a 44 magnum, and started blasting the sign.
Whole point being, the shots need not be from a moving vehicle, esp. in a more remote area.
And other cars.
See post #4. 
It would be wrong to assume that.
