You can’t just choose any random person to be your cultural guide. It makes me completely crazy when people say “My Luisitanian colleague says our poster and brochures are fine” and then assumes their messages are acceptable in Luisitania. One person cannot vouch for everyone in the country.
Most countries are multicultural, including different ethnic and linguistic groups. Not to mention differences between rich and poor, and city and country. It’s not easy to know the tastes and opinions of an entire nation. There’s also a training issue. Your average engineer or doctor from the capital city isn’t in the habit of thinking about the attitudes and mores of everyone around him. An accountant is not an anthropologist.
Most of us can only speak for a limited number of people like ourselves; coming from a developing country doesn’t give you any magic ability to speak for everyone who holds the same passport.
ETA: One great example. The Indian Vogue fashion spread discussed here was designed and shot by Indians.