Why have the Americans developed space shuttle according to the passage?

Ever since the Apollo moon landings, the idea of human expeditions to the Mars has come up repeatedly as the kind of grand adventures that would give focus, purpose, and inspirational lift to the space program. But confronted with the cost — estimated at $ 150 billion last week — presidents starting with Richard Nixon and others have flinched and resorted to halfway measures like the shuttle.

More difficult for foreign managers to grasp are the intricacies of culture, such as the advertising staple of humor. "In southern China humour is more slapstick and physical, like you find in Hong Kong movies," Taw says. "In the north, people love clever wordplays, a legacy of traditional Chinese opera and verbal sparring. For national campaigns, the challenge is to tap into a universal interest."