It's pretty common on utility and even some RV's to see tires that are not balanced.
Sure seems silly. Anyone who's mounted a few tires themselves will know damn well that it's a bad idea not to.
I once bought a car for $100 because the person was convinced it had transmission issues. It needed the wheels balanced (they had taken the weights off to paint the wheels, presumably). Drove it for a while, sold it to a friend for good money and he's still driving it today as a beater.
Tires need balanced on anything that's going to go highway speeds, anything. Rock crawlers, golf cars and lawn mowers are the type of exceptions.