In Thailand people did not use chopsticks for eating until fairly recently; traditionally, they used their hands. Today, however, only sticky rice is still eaten with the hands. Chopsticks are mostly used for consuming noodles (pad thai, noodle soup, and so on); I find this a little perverse, as slippery noodles are among the more difficult foods to eat with chopsticks. Jasmine rice, served curries, stir fries, and the like, is eaten with a spoon. A typical table setting in Thailand will provide the diner with a fork and a spoon; the spoon is the main utensil, and the fork is just used for pushing food onto the spoon. It may feel odd to you at first, but I quickly became habituated to using a spoon, and feel weird now if I have to eat rice with a fork.
So when you go to your favourite Thai restaurant for rice and tasty accompaniments and they bring you chopsticks, know that this is not traditional at all; they're just tired of silly farang asking for chopsticks in an ill-advised attempt to be authentic.
The use of a spoon and a fork for eating, as opposed to the hands, was at one point encouraged by the Thai government. Under the leadership of Prime Minister Phibun Songkram in the 1930s and 40s, the government attempted to solidify and legislate what "Thai-ness" should entail. Songkram's cultural reforms aimed at remaking the exterior of the Thai people into a form that was basically western in origin. The government tried to mold publicly visible performative aspects of Thai-ness like etiquette, dress, hygiene, and comportment, to resemble "civilized" western norms. Thus people were advised by public education campaigns to use a spoon and a fork to eat, wear western-derived clothing (pants, shirts, and hats for men, skirts, bras, and blouses for women), wash well, and be quiet and polite in public. The reforms reached an absurdly invasive level: men were exhorted to kiss their wives good-bye before going off to work, and extend a similar greeting on their return. (Thai do not traditionally kiss as farang do, instead holding their cheek against their loved one's cheek and sniffing; a "Thai kiss", one Thai friend calls this.) Though these government policies were much hated and mocked at the time, many of them were ultimately successful: Thai people today do, by and large, use western utensils for eating and wear western clothing.
Kobkua Suwannathat-Pian's interesting biography of Phibun Songkram, Thailand's Durable Premier: Phibun Through Three Decades 1932-19, has fascinating details about his policies and the ideas that lay behind them.