you might be able to get a net put up, but aside from that, there's usually not much you can do about it. there's a golf course near here run by the county park, and one hole parallels a moderate-traffic road. there is a net separating the fairway and road, and the net is probably almost 30 feet tall so it actually does the job most of the time. however, its not perfect, as some people can really butcher trying to hit a long drive (my friend lives across the street from said fairway and has had his kitchen window broken 3 times and finds dozens of golf balls in his yard every month in the summer).
so one day, someone was driving a nice car back from an auto show, and got hit by an errant shot. ball did a decent amount of damage to the car, can't remember how much but i'd like to say between $2k and $4k. sued the county, but they're not held liable for errant balls hit on their course, and i believe they ruled that the golfer is not liable either (not sure on that part) so this guy got gouged for the repair costs.
sucks, but theres not much you can do in this situation. even good golfers can make mistakes that go over the net, and it'd be tough to hold anyone responsible for the damages apparently.