>Is it really that different? There are some people who are good and some people who end up being opportunistic in evil ways. The more I learn about differences across cultures, the more I conclude that the differences are always ones of degree, and the differences are made more visible due to the cultural contrasts.

Exactly. When you have a culture that more often accepts scams as necessary to succeed and another culture that shuns them, you will probably see disparities in the percentages of people in those cultures who are willing to scam. Ostracism is a powerful deterrent.