The Party is a large part of the difference in culture. Taiwanese and Singaporeans are Chinese but they didn’t have the Cultural Revolution or the Great Leap Forward to deal with. Communism does bad things to cultures. I’m sure things will get better in time but I doubt it will be the work of just one generation.
Lee Kuan Yew famously fashioned Singaporean culture almost out of whole cloth as he believed that without a radical transformation in the social and economic culture that Singapore would quickly disintegrate. I can't find good quotes at the moment, but he had some really harsh opinions about the local ethnic Chinese culture from which he emerged; that it was corrupt, chaotic, criminal and an existential threat to the new nation.
I read Paul Midler's "What's Wrong With China" recently, the followup to his "Poorly Made In China", and his research seems to indicate that communism and the Great Leap Forward are not the source of those aspects of Chinese culture, that those aspects go back much further.
Definitely a fascinating read.