Why hasn't there been a single Tibetan to head the TAR in the 60 years.?

China invaded Tibet in 1949. Chinese say they liberated Tibetans from feudalism and imperialism. Eventhough the fact has been otherwise. But since its occupation, in the last 60 years, there has been not a single Tibetan to be appointed as Party head in Tibet. It was always a Han Chinese who had just no clue about Tibetan culture and identity. What could be the reason? Are Han Chinese racist? Are Tibetans really outsiders who are being colonized? Do Chinese look at Tibetans are Barbarians? Was there not a single Tibetan the Chinese could trust? Or is it just the truth that China has occupied Tibet and it will govern Tibet like any other colony?