The neighboring school district to ours has 25% Spanish-speaking children. Many speak no English at all when the enter school. They also have a sizable Pakistani population, whose kids speak Punjabi.
Their GT director told me they use the Raven's test because it is "culturally fair" for children who may be gifted but don't speak English. I think that's why many districts use it. Not because it's such a great IQ test but because many IQ tests have a huge verbal part, and if English isn't your native language, it might be difficult for you.
