Most country people are private by nature. You hardly ever see their homes from the road. Just like city folks they like to boast a little and keep up with their neighbors. So they build gates as a way of evoking status and advertising a certain position in life.
Some of the grandest entrances are erected by part-time ranchers from the city who buy properties for recreation and hunting. Most don’t actually live in the country except for weekends and holidays, still it is always important to mark your territory. Just one of those ancient instincts you could say.